Propensity Score Matching in R (My first post in blogger)

Author

Andrés Gutiérrez

Published

November 14, 2014

My first post in blogger is about Propensity Score Matching (PSM) in R. In this post I will introduce the R packages MatchIt and Zelig. The first one is devoted to perform different PSM algorithms and the other one is used in order to estimate the average treatment effect (ATE) and the effect of the treatment on the treated (ATT). First of all, I will simulate a population where some individuals receive the treatment, and the remaining ones do not.

rm(list=ls())
library(MatchIt)
# Zelig is no longer available on CRAN; the equivalent analyses below use lm().
N <- 1000
x1 <- round(rnorm(N,20,4))
x2 <- round(rnorm(N,80,10))
f <- 1 + 1*x1 - 0.28*x2
p <- exp(f)/(1+exp(f))
plot(p)

z <- rbinom(N,1, p)
table(z)
0 1
634 366
y <- rep(0, times=N)
# Different values for y over z# The mean difference for y is 5000
y[z == 1] <- 9000 + 2*x1[z == 1] + 0.5*x2[z == 1]
y[z == 0] <- 4000 + 2*x1[z == 0] + 0.5*x2[z == 0]
y <- jitter(y, amount=1000,factor=2)
Data <- data.frame(y=y, x1=x1, x2=x2, z)
# The treatment population
Treats <- subset(Data, z == 1)
colMeans(Treats)
         y         x1         x2          z 
9120.86681   22.78754   74.20397    1.00000 
# The control population
Control <- subset(Data, z == 0)
colMeans(Control)
         y         x1         x2          z 
4091.96471   17.99691   83.44359    0.00000 
# Computing the real effect of the treatment
model <- lm(y ~ z + x1 + x2,data=Data)
Effect <- model$coeff[2]
Effect
       z 
5026.857 

Then I will run a logistic regression in order to estimate the propensity scores. That is the probability of receiving the treatment.

# The propensity scores
ps.model <- glm(z ~ x1 + x2,family = binomial(link = "logit"),data = Data)
plot(ps.model$fitted)

summary(ps.model)

Call:
glm(formula = z ~ x1 + x2, family = binomial(link = "logit"), 
    data = Data)

Coefficients:
            Estimate Std. Error z value Pr(>|z|)    
(Intercept)  1.28473    1.07836   1.191    0.234    
x1           0.99640    0.07476  13.328   <2e-16 ***
x2          -0.28420    0.02246 -12.651   <2e-16 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

(Dispersion parameter for binomial family taken to be 1)

    Null deviance: 1298.57  on 999  degrees of freedom
Residual deviance:  470.03  on 997  degrees of freedom
AIC: 476.03

Number of Fisher Scoring iterations: 7
Data$ps <- ps.model$fitted
table(Data$z)

  0   1 
647 353 
hist(Data$ps[z==1])

hist(Data$ps[z==0])

After that, one may use different matching algorithms. Exact matching is a technique used to match individuals based on the exact values of covariates.

# Exact matching
m1.ps <- matchit(z ~ x1 + x2, method = "exact", data = Data)
summary(m1.ps, covariates = T)

Call:
matchit(formula = z ~ x1 + x2, data = Data, method = "exact")

Summary of Balance for All Data:
   Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean eCDF Max
x1       22.7875       17.9969          1.5648     0.8264    0.1993   0.5562
x2       74.2040       83.4436         -0.9872     1.0623    0.1589   0.3919

Summary of Balance for Matched Data:
   Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean eCDF Max
x1       20.9794       20.9794               0     0.9907         0        0
x2       77.9897       77.9897               0     0.9907         0        0
   Std. Pair Dist.
x1               0
x2               0

Sample Sizes:
              Control Treated
All            647.       353
Matched (ESS)   51.16      97
Matched         95.        97
Unmatched      552.       256
Discarded        0.         0
m1.data <- match.data(m1.ps)

Nearest neighbour matching (NNM) is an algorithm that matches individuals with controls (it could be more two or more controls per treated unit) one by one based on a distance.

#Nearest neighbor matching
m3.ps <- matchit(z ~ x1 + x2, method = "nearest", ratio = 1, data = Data)
summary(m3.ps, covariates = T)

Call:
matchit(formula = z ~ x1 + x2, data = Data, method = "nearest", 
    ratio = 1)

Summary of Balance for All Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.1135          2.6166     1.6655    0.4027
x1             22.7875       17.9969          1.5648     0.8264    0.1993
x2             74.2040       83.4436         -0.9872     1.0623    0.1589
         eCDF Max
distance   0.7901
x1         0.5562
x2         0.3919

Summary of Balance for Matched Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.2063          2.2586     1.2210    0.2663
x1             22.7875       19.7309          0.9984     1.3338    0.1274
x2             74.2040       80.6997         -0.6940     1.1994    0.1120
         eCDF Max Std. Pair Dist.
distance   0.6969          2.2586
x1         0.4193          1.2020
x2         0.2861          1.1850

Sample Sizes:
          Control Treated
All           647     353
Matched       353     353
Unmatched     294       0
Discarded       0       0
plot(m3.ps)

plot(m3.ps, type="jitter")

To identify the units, use first mouse button; to stop, use second.
plot(m3.ps, type="hist")

m3.data <- match.data(m3.ps)
m3.ps$match.matrix
     [,1] 
3    "687"
5    "316"
10   "101"
11   "623"
16   "252"
17   "274"
18   "389"
21   "845"
23   "592"
25   "997"
29   "629"
31   "614"
33   "979"
35   "731"
47   "481"
51   "591"
55   "908"
60   "125"
61   "423"
63   "750"
64   "181"
66   "710"
67   "878"
73   "691"
74   "972"
75   "581"
77   "677"
79   "529"
81   "888"
84   "802"
85   "19" 
88   "365"
89   "327"
90   "595"
92   "701"
96   "456"
97   "363"
99   "443"
100  "850"
109  "478"
112  "627"
113  "510"
114  "530"
115  "319"
116  "108"
117  "607"
118  "727"
119  "909"
120  "500"
123  "298"
126  "337"
130  "276"
139  "457"
140  "106"
142  "398"
154  "630"
155  "72" 
156  "603"
163  "187"
164  "590"
166  "401"
167  "95" 
168  "557"
174  "650"
177  "579"
184  "735"
185  "386"
189  "986"
192  "488"
194  "572"
196  "157"
198  "876"
205  "970"
213  "982"
215  "268"
216  "915"
217  "366"
219  "358"
220  "856"
221  "822"
222  "195"
223  "233"
227  "434"
230  "995"
231  "279"
236  "545"
237  "188"
238  "757"
241  "50" 
242  "618"
246  "823"
247  "361"
249  "773"
250  "475"
255  "248"
256  "98" 
269  "463"
271  "874"
278  "507"
284  "415"
286  "391"
289  "416"
290  "28" 
291  "576"
293  "209"
297  "345"
304  "452"
305  "54" 
306  "924"
309  "333"
310  "105"
311  "9"  
313  "172"
315  "936"
318  "699"
321  "159"
324  "904"
343  "641"
347  "129"
348  "368"
351  "906"
354  "957"
357  "431"
359  "883"
362  "718"
364  "424"
367  "462"
369  "245"
373  "76" 
378  "679"
379  "751"
382  "153"
387  "604"
392  "534"
394  "913"
395  "490"
399  "978"
402  "825"
403  "160"
405  "826"
406  "244"
409  "325"
411  "445"
413  "839"
414  "593"
421  "797"
422  "542"
427  "503"
428  "208"
429  "183"
430  "270"
435  "326"
436  "151"
437  "994"
438  "146"
441  "330"
444  "133"
446  "955"
447  "835"
450  "334"
455  "36" 
461  "568"
464  "111"
465  "763"
466  "285"
468  "776"
470  "383"
471  "528"
472  "8"  
473  "388"
477  "301"
480  "990"
483  "320"
484  "296"
485  "884"
487  "384"
491  "26" 
494  "175"
504  "454"
506  "143"
508  "624"
509  "141"
516  "719"
517  "857"
521  "818"
523  "102"
525  "846"
527  "65" 
537  "752"
538  "127"
540  "170"
543  "329"
544  "27" 
548  "968"
550  "779"
553  "169"
558  "738"
559  "39" 
560  "775"
561  "355"
569  "68" 
570  "493"
577  "94" 
578  "193"
582  "197"
584  "786"
588  "774"
594  "754"
597  "336"
598  "684"
600  "328"
601  "815"
605  "791"
606  "397"
609  "721"
610  "535"
611  "32" 
615  "121"
619  "573"
620  "149"
628  "70" 
631  "229"
635  "621"
636  "199"
638  "661"
640  "840"
643  "659"
644  "877"
645  "235"
647  "13" 
652  "349"
654  "780"
655  "862"
657  "486"
658  "404"
660  "58" 
662  "520"
663  "283"
664  "182"
665  "927"
666  "695"
668  "335"
669  "844"
671  "150"
674  "206"
675  "949"
676  "272"
680  "41" 
682  "967"
683  "795"
685  "939"
686  "962"
689  "400"
692  "863"
693  "905"
694  "810"
700  "69" 
715  "225"
716  "396"
717  "812"
723  "602"
730  "801"
733  "998"
734  "356"
739  "267"
741  "549"
745  "107"
746  "965"
747  "743"
748  "40" 
753  "809"
758  "940"
759  "744"
761  "59" 
769  "469"
771  "253"
777  "616"
778  "678"
781  "617"
783  "161"
787  "519"
792  "410"
796  "985"
799  "374"
803  "372"
807  "891"
811  "260"
814  "993"
817  "377"
819  "78" 
821  "224"
824  "203"
827  "867"
832  "322"
834  "138"
836  "533"
837  "875"
838  "346"
842  "46" 
849  "622"
851  "782"
852  "926"
853  "847"
854  "152"
855  "869"
858  "370"
859  "190"
860  "790"
864  "898"
865  "564"
866  "724"
868  "755"
870  "281"
872  "331"
873  "670"
885  "999"
887  "562"
892  "302"
894  "637"
897  "264"
899  "765"
900  "265"
902  "612"
903  "459"
911  "907"
920  "344"
922  "353"
928  "2"  
929  "554"
930  "134"
931  "261"
932  "62" 
938  "262"
941  "793"
943  "749"
944  "482"
945  "698"
946  "536"
948  "412"
950  "890"
951  "433"
961  "340"
963  "259"
969  "43" 
973  "772"
975  "639"
976  "228"
977  "186"
984  "93" 
989  "44" 
992  "385"
996  "12" 
1000 "460"
Pairs <- cbind(Data[row.names(m3.ps$match.matrix),], Data[m3.ps$match.matrix,])
Pairs
             y x1  x2 z          ps        y x1  x2 z          ps
3    10063.205 23  76 1 0.931027491 3160.657 21  86 0 0.096892912
5     9705.856 26  70 1 0.999322883 4548.612 22  80 0 0.615235752
10    8759.264 20  73 1 0.614433803 3306.336 20  87 0 0.028949215
11    8789.761 20  78 1 0.277876327 4613.367 19  86 0 0.014414046
16    8433.025 23  69 1 0.989968995 3257.432 21  81 0 0.307629262
17    8823.235 26  72 1 0.998805205 3735.166 19  70 0 0.579858911
18    9172.051 19  76 1 0.200525046 3964.997 18  83 0 0.012507663
21    8189.328 28  74 1 0.999712207 3459.289 20  72 0 0.679220102
23    8248.042 23  85 1 0.511189473 3418.535 20  88 0 0.021944768
25    8988.314 24  80 1 0.921447105 4065.890 17  72 0 0.096301872
29    8276.923 22  76 1 0.832880575 5052.542 14  63 0 0.064743360
31    9489.524 20  78 1 0.277876327 3421.752 19  86 0 0.014414046
33    8236.849 27  68 1 0.999858319 3452.033 22  78 0 0.738421072
35    9715.245 23  58 1 0.999555543 5082.799 28 101 0 0.617637828
47    8581.192 20  69 1 0.832408685 3654.491 17  74 0 0.056925008
51    8121.518 23  82 1 0.710408842 3588.038 17  75 0 0.043454549
55    9021.084 20  72 1 0.679220102 3362.499 18  79 0 0.037978361
60    8619.468 20  70 1 0.788947598 4420.698 18  78 0 0.049839708
61    8516.199 26  88 1 0.898562905 3795.357 20  83 0 0.085018977
63    9327.283 19  65 1 0.851093425 5049.109 18  77 0 0.065154678
64    8694.914 22  74 1 0.897943907 3969.973 20  83 0 0.085018977
66    9850.745 22  85 1 0.278556361 4430.712 21  93 0 0.014462234
67    9595.795 19  57 1 0.982308420 3690.397 20  79 0 0.224571440
73    9816.380 24  74 1 0.984743618 4447.631 18  71 0 0.277197315
74    8472.126 19  78 1 0.124398661 4657.404 17  80 0 0.010850639
75    9324.843 22  78 1 0.738421072 3173.394 21  89 0 0.043736943
77    8703.039 24  75 1 0.979829980 4142.515 25  97 0 0.202158682
79    8760.662 26  63 1 0.999907333 4076.043 24  85 0 0.739074650
81    9699.242 19  73 1 0.370421056 3322.930 22  96 0 0.016661501
84    9117.942 31  91 1 0.998186622 4561.407 18  67 0 0.544482128
85    9459.019 22  70 1 0.964817558 3459.873 19  77 0 0.158795476
88    9524.842 20  75 1 0.474418575 3255.879 16  74 0 0.021799870
89    8576.767 30 105 1 0.791753158 3670.894 20  85 0 0.050000319
90    9108.723 19  70 1 0.579858911 3685.462 21  91 0 0.025252745
92    8301.088 24  85 1 0.739074650 3657.659 16  71 0 0.049679585
96    8781.966 22  65 1 0.991271548 3382.339 23  88 0 0.308351017
97    8190.420 25  83 1 0.931244634 4106.513 23  93 0 0.097189644
99    8350.664 31  92 1 0.997591998 4347.073 20  75 0 0.474418575
100   8893.035 21  74 1 0.764621449 4715.693 16  71 0 0.049679585
109   8710.371 23  76 1 0.931027491 3429.858 21  86 0 0.096892912
112   9323.273 21  77 1 0.580683696 3813.462 21  91 0 0.025252745
113   8983.719 24  82 1 0.869184755 4608.771 17  73 0 0.074247052
114   9217.271 20  81 1 0.140925361 3430.843 19  87 0 0.010887046
115   8134.586 21  79 1 0.439590841 4135.298 21  92 0 0.019125067
116   8270.879 24  83 1 0.833351401 3725.726 16  70 0 0.064948716
117   9256.702 19  71 1 0.509496988 4977.148 18  81 0 0.021872202
118  10052.430 20  76 1 0.404531992 4893.147 19  85 0 0.019061644
119   8729.021 20  70 1 0.788947598 3582.514 16  71 0 0.049679585
120   8856.850 22  76 1 0.832880575 4709.535 23  95 0 0.057472865
123   9688.339 21  76 1 0.647891157 3852.608 21  90 0 0.033277126
126   9861.592 17  58 1 0.850663742 4306.987 16  70 0 0.064948716
130   8684.901 30  74 1 0.999960760 3766.032 24  84 0 0.790073132
139   9704.264 21  71 1 0.883992214 4396.007 21  87 0 0.074713924
140   8536.793 25  84 1 0.910663678 3291.898 15  65 0 0.096007562
142   8156.267 21  67 1 0.959596552 4107.493 18  74 0 0.140515881
154   9310.721 19  65 1 0.851093425 4115.816 18  77 0 0.065154678
155   8139.426 29  85 1 0.997583850 4531.086 20  75 0 0.474418575
156   8773.188 21  71 1 0.883992214 3692.977 19  80 0 0.074480152
163   9368.322 29  68 1 0.999980685 3831.602 27  93 0 0.852801965
164   9036.764 26  84 1 0.965046737 4587.618 21  84 0 0.159248355
166   8996.454 22  68 1 0.979762945 3914.979 23  90 0 0.201613035
167   9553.791 23  69 1 0.989968995 3743.188 21  81 0 0.307629262
168   8230.864 22  84 1 0.339072068 3729.481 20  89 0 0.016606109
174   9799.736 18  69 1 0.403716516 3904.217 19  85 0 0.019061644
177   8315.752 27  77 1 0.998174321 3474.498 25  92 0 0.512035622
184   8937.535 26  93 1 0.681429563 4308.630 20  86 0 0.038102281
185   9649.252 30  96 1 0.980029784 3941.531 18  72 0 0.223982281
189  10036.312 25  77 1 0.986759911 3364.974 22  85 0 0.278556361
192   9919.054 22  71 1 0.953787482 3118.172 19  78 0 0.124398661
194   9054.288 18  50 1 0.993372179 4521.036 21  80 0 0.371211147
196   8119.149 21  76 1 0.647891157 4302.487 21  90 0 0.033277126
198   9408.028 22  72 1 0.939516140 3424.183 27 107 0 0.097785543
205   9027.826 19  57 1 0.982308420 4744.342 18  72 0 0.223982281
213   9896.261 23  66 1 0.995699002 3832.287 18  69 0 0.403716516
215   9404.786 25  58 1 0.999939391 4772.660 19  67 0 0.764011430
216   9152.874 18  68 1 0.473574259 4088.401 23  99 0 0.019188698
217   9070.869 21  78 1 0.510343260 4726.676 20  88 0 0.021944768
219   9536.295 29  77 1 0.999750742 3688.849 21  75 0 0.709711664
220   9222.398 28  76 1 0.999492028 5083.920 24  87 0 0.616037075
221   9955.165 23  83 1 0.648663308 3763.615 21  90 0 0.033277126
222   8455.751 18  65 1 0.678481820 3566.131 18  79 0 0.037978361
223   8476.346 24  77 1 0.964932328 3843.996 21  84 0 0.159248355
227   8190.552 24  85 1 0.739074650 3439.161 16  71 0 0.049679585
230   8500.147 23  69 1 0.989968995 4076.849 19  74 0 0.306908446
231   8292.887 18  70 1 0.337555917 4496.564 20  89 0 0.016606109
236   8155.931 28  75 1 0.999617645 4943.073 21  76 0 0.647891157
237   8361.284 22  69 1 0.973288688 5060.458 20  80 0 0.178957916
238   8964.878 25  79 1 0.976859852 3195.795 26 101 0 0.180455509
241   8612.428 22  71 1 0.953787482 4816.215 19  78 0 0.124398661
242   8626.602 22  55 1 0.999486844 3285.766 22  80 0 0.615235752
246   9796.252 22  70 1 0.964817558 4764.508 17  70 0 0.158343642
247  10064.063 23  82 1 0.710408842 3148.260 17  75 0 0.043454549
249   9443.321 23  69 1 0.989968995 5042.336 19  74 0 0.306908446
250   8281.874 22  82 1 0.475263037 4821.783 18  81 0 0.021872202
255   9645.268 26  76 1 0.996285458 3637.976 20  76 0 0.404531992
256   8505.833 21  78 1 0.510343260 4724.054 20  88 0 0.021944768
269   9991.929 23  76 1 0.931027491 3119.447 21  86 0 0.096892912
271  10052.958 25  85 1 0.884684965 3170.933 21  87 0 0.074713924
278   9414.422 21  82 1 0.250597545 4779.018 17  79 0 0.014366017
284   8439.111 21  50 1 0.999664324 4615.027 25  90 0 0.649434682
286  10052.207 25  80 1 0.969485761 3913.853 18  73 0 0.178460883
289   8605.068 22  82 1 0.475263037 4384.436 18  81 0 0.021872202
290   8518.714 19  72 1 0.438756765 4939.092 21  92 0 0.019125067
291   9652.115 23  75 1 0.947189168 4466.576 20  82 0 0.109893723
293   8206.735 20  75 1 0.474418575 3260.781 16  74 0 0.021799870
297   9768.883 19  81 1 0.057107080 4177.373 22  98 0 0.009506231
304   9926.004 21  66 1 0.969284761 4076.939 16  66 0 0.177964931
305   8355.090 24  94 1 0.179955228 4746.976 18  83 0 0.012507663
306  10043.549 23  77 1 0.910387791 4634.916 22  90 0 0.085282779
309   9232.894 24  86 1 0.680693976 3604.583 20  86 0 0.038102281
310   8609.751 27  69 1 0.999811757 3529.923 23  82 0 0.710408842
311   9070.206 21  80 1 0.371211147 3385.246 17  78 0 0.018998427
313   9384.540 22  74 1 0.897943907 3312.147 20  83 0 0.085018977
315  10005.416 22  80 1 0.615235752 3812.498 20  87 0 0.028949215
318   8415.244 22  80 1 0.615235752 4267.990 20  87 0 0.028949215
321   9261.289 25  77 1 0.986759911 4880.289 22  85 0 0.278556361
324   8160.594 21  78 1 0.510343260 4185.908 18  81 0 0.021872202
343   9668.226 24  65 1 0.998801157 3473.282 17  63 0 0.579033680
347   9321.374 20  67 1 0.897633155 3237.670 18  76 0 0.084755914
348   8914.603 23  74 1 0.959727643 4706.045 20  81 0 0.140925361
351   8119.209 19  73 1 0.370421056 5001.261 20  89 0 0.016606109
354   9389.141 22  76 1 0.832880575 4780.139 21  88 0 0.057289698
357   9046.107 24  82 1 0.869184755 4194.928 17  73 0 0.074247052
359   9942.282 21  53 1 0.999212942 4242.838 20  73 0 0.614433803
362   8998.446 23  65 1 0.996759557 4572.975 19  72 0 0.438756765
364   8118.007 23  83 1 0.648663308 4546.985 21  90 0 0.033277126
367   9655.120 22  73 1 0.921201637 4618.401 17  72 0 0.096301872
369   8536.379 30  86 1 0.998813260 3324.102 21  77 0 0.580683696
373   8285.052 22  77 1 0.789510917 3660.493 20  85 0 0.050000319
378   9507.320 22  77 1 0.789510917 4662.885 18  78 0 0.049839708
379   8349.869 24  72 1 0.991300799 4337.673 20  77 0 0.338313577
382   9678.451 28  91 1 0.965160787 4949.419 16  66 0 0.177964931
387   8202.671 18  57 1 0.953488036 4369.485 22  89 0 0.110225411
392   9826.312 21  64 1 0.982367175 4693.392 24  93 0 0.225753057
394   9122.539 20  68 1 0.868412737 4712.556 20  84 0 0.065361248
395   8441.566 24  62 1 0.999488578 3427.332 24  87 0 0.616037075
399   9896.750 23  66 1 0.995699002 3653.354 18  69 0 0.403716516
402   9533.508 19  74 1 0.306908446 3917.424 16  75 0 0.016495867
403   8974.255 26  95 1 0.547839674 3589.605 19  84 0 0.025169522
405   8942.022 21  69 1 0.930809713 3190.460 19  79 0 0.096596988
406   8747.899 21  70 1 0.910111136 4826.418 22  90 0 0.085282779
409   9691.459 21  68 1 0.947019516 3622.643 20  82 0 0.109893723
411   8480.075 26 102 1 0.142159789 4958.331 14  69 0 0.012424285
413   8091.298 21  83 1 0.201068490 4627.313 20  90 0 0.012549558
414   8308.879 20  63 1 0.964702426 4394.633 22  88 0 0.141335839
421   9261.591 28  62 1 0.999990492 4546.530 23  75 0 0.947189168
422   8701.330 23  84 1 0.581508030 4500.648 16  73 0 0.028759428
427   9316.743 20  83 1 0.085018977 3830.132 17  80 0 0.010850639
428   8290.262 23  84 1 0.581508030 3559.140 16  73 0 0.028759428
429   8270.488 28  78 1 0.999103552 3195.390 18  66 0 0.613631233
430   9420.592 20  74 1 0.545321906 3710.020 17  77 0 0.025086566
435   9825.739 25  90 1 0.649434682 3340.577 16  72 0 0.037854828
436   9742.111 23  88 1 0.308351017 3751.969 20  89 0 0.016606109
437   8161.450 26  79 1 0.991329954 3786.049 20  77 0 0.338313577
438   8454.059 24  67 1 0.997885448 3087.984 19  71 0 0.509496988
441   8825.902 25  80 1 0.969485761 3645.211 18  73 0 0.178460883
444   8739.745 21  63 1 0.986671133 4885.968 20  78 0 0.277876327
446   9319.413 24  71 1 0.993438732 3263.481 21  80 0 0.371211147
447   8343.560 25  86 1 0.852376356 3513.789 20  84 0 0.065361248
450   9411.461 15  61 1 0.248694489 4780.506 22  97 0 0.012591592
455   9586.175 21  65 1 0.976706259 3791.226 22  87 0 0.179456031
461   9748.195 25  78 1 0.982484112 3795.292 19  75 0 0.249962118
464   9414.435 19  56 1 0.986626524 3663.815 20  78 0 0.277876327
465   9081.892 18  69 1 0.403716516 3801.045 17  78 0 0.018998427
466   9830.065 26  88 1 0.898562905 4231.355 20  83 0 0.085018977
468   9725.604 24  78 1 0.953936515 3342.331 19  78 0 0.124398661
470   9497.040 23  83 1 0.648663308 3861.137 21  90 0 0.033277126
471  10065.244 25  93 1 0.441260013 3367.179 21  92 0 0.019125067
472   8892.571 22  79 1 0.679957488 4289.723 20  86 0 0.038102281
473   8595.018 23  76 1 0.931027491 4905.844 21  86 0 0.096892912
477   9980.913 21  79 1 0.439590841 4531.763 21  92 0 0.019125067
480   9759.734 23  65 1 0.996759557 4270.356 22  83 0 0.405347997
483   9931.586 25  80 1 0.969485761 3535.805 18  73 0 0.178460883
484   8936.788 22  82 1 0.475263037 4580.260 18  81 0 0.021872202
485   8369.125 19  73 1 0.370421056 3623.627 20  89 0 0.016606109
487   9583.058 22  80 1 0.615235752 4353.505 20  87 0 0.028949215
491   9130.948 25  90 1 0.649434682 4789.753 16  72 0 0.037854828
494   8685.271 18  69 1 0.403716516 4918.379 17  78 0 0.018998427
504   9653.641 20  69 1 0.832408685 4808.642 17  74 0 0.056925008
506   9843.296 20  75 1 0.474418575 3722.363 16  74 0 0.021799870
508   8113.734 23  80 1 0.812414196 4093.411 15  67 0 0.056743482
509   9578.616 22  62 1 0.996260309 3754.009 20  76 0 0.404531992
516   9295.038 27  58 1 0.999991738 4341.911 20  63 0 0.964702426
517   9693.419 30  75 1 0.999947863 4536.841 22  77 0 0.789510917
521   9173.679 24  82 1 0.869184755 4213.439 22  91 0 0.065568426
523   8827.148 21  68 1 0.947019516 3801.285 20  82 0 0.109893723
525   9938.390 20  73 1 0.614433803 3193.754 18  80 0 0.028854170
527   8883.776 19  64 1 0.883644485 3762.962 19  80 0 0.074480152
537   8771.457 19  66 1 0.811379847 5025.034 20  85 0 0.050000319
538   9316.234 26  80 1 0.988512838 4950.287 19  74 0 0.306908446
540   9003.491 24  75 1 0.979829980 3750.268 25  97 0 0.202158682
543   8770.785 23  63 1 0.998161937 3370.383 19  71 0 0.509496988
544   9698.870 20  60 1 0.984641531 4759.155 21  82 0 0.250597545
548   8553.925 27  79 1 0.996781360 3708.935 19  72 0 0.438756765
550   8148.534 22  76 1 0.832880575 5064.087 19  81 0 0.057107080
553   9122.285 23  74 1 0.959727643 4656.117 20  81 0 0.140925361
558   9616.789 24  66 1 0.998407724 4323.322 20  74 0 0.545321906
559   9108.177 24  67 1 0.997885448 3617.278 19  71 0 0.509496988
560   9289.606 17  57 1 0.883295851 3862.948 17  73 0 0.074247052
561   8548.169 24  72 1 0.991300799 4157.915 20  77 0 0.338313577
569   8708.500 22  81 1 0.546161426 3725.990 19  84 0 0.025169522
570   8230.249 22  72 1 0.939516140 4514.903 23  93 0 0.097189644
577   9275.231 16  58 1 0.677742646 4481.920 18  79 0 0.037978361
578   9006.976 23  65 1 0.996759557 4082.801 22  83 0 0.405347997
582   8377.612 28  81 1 0.997899691 4441.679 19  71 0 0.509496988
584   8877.054 22  75 1 0.868799228 4944.180 22  91 0 0.065568426
588   9899.855 25  80 1 0.969485761 3637.471 16  66 0 0.177964931
594   8280.168 28  78 1 0.999103552 4266.283 21  77 0 0.580683696
597   9666.974 21  60 1 0.994274081 3517.968 23  87 0 0.372001927
598   9065.296 22  76 1 0.832880575 4909.346 19  81 0 0.057107080
600   9909.194 19  68 1 0.709013494 4953.035 22  93 0 0.038226589
601   9711.214 23  64 1 0.997559238 3457.374 18  68 0 0.473574259
605   9961.203 20  71 1 0.737766439 3108.033 19  82 0 0.043595528
606  10000.974 21  73 1 0.811897568 4917.363 22  92 0 0.050161420
609   9846.051 24  75 1 0.979829980 3467.874 23  90 0 0.201613035
610   9010.990 26  69 1 0.999490306 3392.080 24  87 0 0.616037075
611   9043.765 22  68 1 0.979762945 4959.721 23  90 0 0.201613035
615   9667.326 24  68 1 0.997192344 3782.931 21  79 0 0.439590841
619   8619.818 27  85 1 0.982542294 3223.524 19  75 0 0.249962118
620   8611.190 22  82 1 0.475263037 4768.974 18  81 0 0.021872202
628   9535.096 24  65 1 0.998801157 3336.727 17  63 0 0.579033680
631   8996.625 21  83 1 0.201068490 4978.838 20  90 0 0.012549558
635   8411.801 24  58 1 0.999835857 4517.031 22  78 0 0.738421072
636   9844.647 22  73 1 0.921201637 4600.600 15  65 0 0.096007562
638   9692.800 22  82 1 0.475263037 3718.050 16  74 0 0.021799870
640   9759.973 21  80 1 0.371211147 4288.910 15  71 0 0.018935415
643   9341.530 25  90 1 0.649434682 4056.878 14  65 0 0.037731681
644   9097.679 20  71 1 0.737766439 4281.972 17  75 0 0.043454549
645   8961.481 23  72 1 0.976783179 4591.927 22  87 0 0.179456031
647   9524.166 18  71 1 0.277197315 4249.309 19  86 0 0.014414046
652   8677.993 21  71 1 0.883992214 4673.457 19  80 0 0.074480152
654   8138.474 20  73 1 0.614433803 3686.546 18  80 0 0.028854170
655   9844.808 22  85 1 0.278556361 4744.370 19  86 0 0.014414046
657   8510.441 22  67 1 0.984692658 4696.832 21  82 0 0.250597545
658   9221.766 24  77 1 0.964932328 4203.980 19  77 0 0.158795476
660   9356.284 24  67 1 0.997885448 4531.060 22  82 0 0.475263037
662   9836.159 26  83 1 0.973464204 4645.562 20  80 0 0.178957916
663   9888.191 18  77 1 0.065154678 4989.183 13  66 0 0.010778187
664   9360.120 24  74 1 0.984743618 4654.608 18  71 0 0.277197315
665   8431.482 26  59 1 0.999970267 4567.696 22  76 0 0.832880575
666   9425.583 20  74 1 0.545321906 4586.345 22  95 0 0.022017569
668   9045.037 23  83 1 0.648663308 4432.423 21  90 0 0.033277126
669   9714.318 30  85 1 0.999106580 3918.885 18  66 0 0.613631233
671   9902.385 22  59 1 0.998402331 3597.790 20  74 0 0.545321906
674   8772.066 21  80 1 0.371211147 3899.471 15  71 0 0.018935415
675   9779.431 21  81 1 0.307629262 4320.953 18  82 0 0.016550898
676   9123.872 26  68 1 0.999616348 4636.373 21  76 0 0.647891157
680   9118.848 22  81 1 0.546161426 3928.217 19  84 0 0.025169522
682   9877.023 21  73 1 0.811897568 3732.042 20  85 0 0.050000319
683   9758.971 23  79 1 0.851949731 3672.480 20  84 0 0.065361248
685   8318.104 28  84 1 0.995087087 3637.931 25  94 0 0.372793394
686   8834.475 22  74 1 0.897943907 3683.068 18  76 0 0.084755914
689   9092.217 20  62 1 0.973200507 3379.247 18  73 0 0.178460883
692   8209.204 24  73 1 0.988474321 4783.862 17  67 0 0.306188572
693   8207.055 27  72 1 0.999558541 4705.610 17  62 0 0.646344537
694   9214.067 20  74 1 0.545321906 3115.949 20  88 0 0.021944768
700   8857.915 19  51 1 0.996737608 5082.830 22  83 0 0.405347997
715   9907.322 21  67 1 0.959596552 4060.123 16  67 0 0.140107396
716   9327.662 15  52 1 0.810341127 3703.936 20  85 0 0.050000319
717  10086.969 25  81 1 0.959858326 4167.778 20  81 0 0.140925361
723   9530.951 25  69 1 0.998620689 4116.149 22  81 0 0.546161426
730   9008.398 22  68 1 0.979762945 3132.943 19  76 0 0.200525046
733   9501.549 25  83 1 0.931244634 3905.312 21  86 0 0.096892912
734  10003.496 22  84 1 0.339072068 4982.467 20  89 0 0.016606109
739   9935.454 20  63 1 0.964702426 3102.088 22  88 0 0.141335839
741   9356.085 19  58 1 0.976629089 4460.763 20  80 0 0.178957916
745   8291.639 24  85 1 0.739074650 3696.189 16  71 0 0.049679585
746   9058.627 22  71 1 0.953787482 4275.412 17  71 0 0.124030268
747   8923.276 19  70 1 0.579858911 3199.457 19  84 0 0.025169522
748   9117.954 25  65 1 0.999557044 3778.927 17  62 0 0.646344537
753  10026.682 21  76 1 0.647891157 3331.939 19  83 0 0.033168357
758   8739.011 25  83 1 0.931244634 4310.834 21  86 0 0.096892912
759   8607.717 21  65 1 0.976706259 3173.547 20  80 0 0.178957916
761   8737.445 25  73 1 0.995713480 5015.905 20  76 0 0.404531992
769   8157.387 22  71 1 0.953787482 4613.179 15  64 0 0.123662813
771   9327.811 22  66 1 0.988435676 3935.257 17  67 0 0.306188572
777   9042.511 21  69 1 0.930809713 4566.430 19  79 0 0.096596988
778   9145.595 20  71 1 0.737766439 3614.355 17  75 0 0.043454549
781   9431.008 19  65 1 0.851093425 3950.395 16  70 0 0.064948716
783   9789.438 29  66 1 0.999989059 4480.375 22  73 0 0.921201637
787  10033.700 25  77 1 0.986759911 4798.640 20  78 0 0.277876327
792   9501.017 17  82 1 0.006175169 4769.599 17  82 0 0.006175169
796   8596.839 19  68 1 0.709013494 3473.114 20  86 0 0.038102281
799   8731.523 19  75 1 0.249962118 4935.013 17  79 0 0.014366017
803   9509.512 24  74 1 0.984743618 3989.823 23  89 0 0.251234047
807   9652.646 22  70 1 0.964817558 4174.019 24  95 0 0.141747314
811   8628.473 21  55 1 0.998611329 4758.149 22  81 0 0.546161426
814   9375.139 23  92 1 0.125138262 4336.254 17  80 0 0.010850639
817   9415.824 26  63 1 0.999907333 4913.931 24  85 0 0.739074650
819   9477.929 26  70 1 0.999322883 5026.756 22  80 0 0.615235752
821   8164.909 19  59 1 0.969183780 4573.342 16  66 0 0.177964931
824   9830.793 26  75 1 0.997201809 4911.846 21  79 0 0.439590841
827   9303.990 24  92 1 0.279237416 4224.286 14  68 0 0.016441016
832   9219.476 21  67 1 0.959596552 3863.213 14  60 0 0.139699906
834   9312.676 25  79 1 0.976859852 3446.375 24  94 0 0.179955228
836   9510.294 25  82 1 0.947358307 5012.410 22  89 0 0.110225411
837   9548.625 21  83 1 0.201068490 3735.015 18  83 0 0.012507663
838   9994.571 21  68 1 0.947019516 3259.661 18  75 0 0.109562910
842   8812.415 27  83 1 0.990036029 3769.511 23  88 0 0.308351017
849  10061.063 22  66 1 0.988435676 3489.379 24  92 0 0.279237416
851  10073.666 19  73 1 0.370421056 4461.740 20  89 0 0.016606109
852   8418.042 22  76 1 0.832880575 3588.470 17  74 0 0.056925008
853   9900.234 28  82 1 0.997211243 4699.492 21  79 0 0.439590841
854   8962.587 27  94 1 0.813444176 3077.864 17  74 0 0.056925008
855   8990.795 23  76 1 0.931027491 4233.272 19  79 0 0.096596988
858   8155.517 25  62 1 0.999811119 4844.151 21  75 0 0.709711664
859   9146.016 21  76 1 0.647891157 3695.342 17  76 0 0.033059932
860   8426.751 18  71 1 0.277197315 4597.203 17  79 0 0.014366017
864  10063.369 29  99 1 0.885374115 4211.637 25 101 0 0.075183493
865   9840.049 26  86 1 0.939899867 3842.442 16  68 0 0.109232971
866   8696.431 31  67 1 0.999998018 5050.338 26  78 0 0.993460769
868   9050.921 21  76 1 0.647891157 4883.102 15  69 0 0.032951850
870  10012.378 22  78 1 0.738421072 3890.864 21  89 0 0.043736943
872   9579.439 21  69 1 0.930809713 4893.802 19  79 0 0.096596988
873   8431.956 27  99 1 0.512881702 3302.124 20  88 0 0.021944768
885   8343.694 22  71 1 0.953787482 3588.777 26 103 0 0.110891418
887   9919.208 19  55 1 0.989901514 3921.689 19  74 0 0.306908446
892   8148.956 26  82 1 0.979896798 4559.346 18  72 0 0.223982281
894   8118.491 22  81 1 0.546161426 4394.837 17  77 0 0.025086566
897   9312.310 23  64 1 0.997559238 3572.118 23  86 0 0.440425259
899   9182.428 21  73 1 0.811897568 3406.904 20  85 0 0.050000319
900   8873.222 22  68 1 0.979762945 4103.937 19  76 0 0.200525046
902   8817.309 20  75 1 0.474418575 3482.710 14  67 0 0.021727773
903   8631.704 22  69 1 0.973288688 3505.314 18  73 0 0.178460883
911   9577.510 29  81 1 0.999223524 4807.917 20  73 0 0.614433803
920   8367.827 27  65 1 0.999939596 4087.288 25  88 0 0.765838210
922   9301.979 27  77 1 0.998174321 4619.310 25  92 0 0.512035622
928   8924.814 27  83 1 0.990036029 4625.083 23  88 0 0.308351017
929   9071.670 27  75 1 0.998965063 3356.189 21  77 0 0.580683696
930   9060.541 21  81 1 0.307629262 3247.475 18  82 0 0.016550898
931   8129.692 22  78 1 0.738421072 3950.700 21  89 0 0.043736943
932   8139.725 22  66 1 0.988435676 4783.892 24  92 0 0.279237416
938   9330.340 28  68 1 0.999947686 4752.035 27  95 0 0.766444950
941   9781.638 26  82 1 0.979896798 3299.474 25  97 0 0.202158682
943   9010.214 26  85 1 0.954085092 3901.443 21  85 0 0.124767992
944   9845.467 16  59 1 0.612828045 4249.283 18  80 0 0.028854170
945   9292.751 22  58 1 0.998797095 3784.042 24  88 0 0.547000683
946   9879.860 27  77 1 0.998174321 4174.790 21  78 0 0.510343260
948   9557.862 22  71 1 0.953787482 4056.185 24  96 0 0.110557975
950   8701.499 25  79 1 0.976859852 3580.496 22  87 0 0.179456031
951   8474.594 20  72 1 0.679220102 3248.846 18  79 0 0.037978361
961  10066.037 21  71 1 0.883992214 3216.871 19  80 0 0.074480152
963   8558.791 29 105 1 0.583978287 4183.886 18  80 0 0.028854170
969   9436.242 26  87 1 0.921691872 5074.048 19  79 0 0.096596988
973   8728.427 14  71 1 0.007075591 4130.988 14  71 0 0.007075591
975   8984.511 20  82 1 0.109893723 3254.130 17  80 0 0.010850639
976   9987.146 28  59 1 0.999995947 3414.553 25  78 0 0.982484112
977   9932.142 23  84 1 0.581508030 4543.395 23  98 0 0.025336236
984   8939.801 22  75 1 0.868799228 3125.927 22  91 0 0.065568426
989   9415.052 22  70 1 0.964817558 4864.085 24  95 0 0.141747314
992  10040.653 22  92 1 0.050161420 3115.820 20  91 0 0.009474397
996   9246.277 23  68 1 0.992431736 3094.405 22  84 0 0.339072068
1000 10042.248 28  65 1 0.999977698 5025.905 21  72 0 0.851522088

Optimal matching solves the problem inherent to the NNM, that matches units one at a time, without taking into account any global (over the entire population) distance measure. This way, with NNM the last treated unit could could match an inappropriate unit.

#Optimal matching
m5.ps <- matchit(z ~ x1 + x2, method = "optimal", data = Data)
summary(m5.ps, covariates = T)

Call:
matchit(formula = z ~ x1 + x2, data = Data, method = "optimal")

Summary of Balance for All Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.1135          2.6166     1.6655    0.4027
x1             22.7875       17.9969          1.5648     0.8264    0.1993
x2             74.2040       83.4436         -0.9872     1.0623    0.1589
         eCDF Max
distance   0.7901
x1         0.5562
x2         0.3919

Summary of Balance for Matched Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.2063          2.2586     1.2210    0.2663
x1             22.7875       19.7422          0.9947     1.3479    0.1269
x2             74.2040       80.7394         -0.6983     1.2004    0.1127
         eCDF Max Std. Pair Dist.
distance   0.6969          2.2586
x1         0.4193          1.2057
x2         0.2890          1.1892

Sample Sizes:
          Control Treated
All           647     353
Matched       353     353
Unmatched     294       0
Discarded       0       0
plot(m5.ps)

plot(m5.ps, type="jitter")

To identify the units, use first mouse button; to stop, use second.
plot(m5.ps, type="hist")

m5.data <- match.data(m5.ps)
# m5.data[(m5.data$subclass == 1),]

Full matching forms subgroups in an optimal way.

#Full matching
m4.ps <- matchit(z ~ x1 + x2, method = "full", data = Data)
summary(m4.ps, covariates = T)

Call:
matchit(formula = z ~ x1 + x2, data = Data, method = "full")

Summary of Balance for All Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.1135          2.6166     1.6655    0.4027
x1             22.7875       17.9969          1.5648     0.8264    0.1993
x2             74.2040       83.4436         -0.9872     1.0623    0.1589
         eCDF Max
distance   0.7901
x1         0.5562
x2         0.3919

Summary of Balance for Matched Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.7904          0.0056     0.9107    0.0181
x1             22.7875       23.1741         -0.1263     1.1357    0.0359
x2             74.2040       77.3825         -0.3396     1.6409    0.0692
         eCDF Max Std. Pair Dist.
distance   0.2153          0.0203
x1         0.1642          0.8179
x2         0.2849          0.9079

Sample Sizes:
              Control Treated
All            647.       353
Matched (ESS)   10.07     353
Matched        647.       353
Unmatched        0.         0
Discarded        0.         0
plot(m4.ps)

plot(m4.ps, type="jitter")

To identify the units, use first mouse button; to stop, use second.
plot(m4.ps, type="hist")

m4.data <- match.data(m4.ps)

Caliper matching is a refinement of the NNM. It defines a constraint over the individual distant measure. So, it minimises the probability of bad matching.

# Caliper matching
sd.ps <- sd(Data$ps)
m8.ps <- matchit(z ~ x1 + x2, method = "nearest", caliper = 0.25 * sd.ps, data = Data)
summary(m8.ps, covariates = T)

Call:
matchit(formula = z ~ x1 + x2, data = Data, method = "nearest", 
    caliper = 0.25 * sd.ps)

Summary of Balance for All Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.7919        0.1135          2.6166     1.6655    0.4027
x1             22.7875       17.9969          1.5648     0.8264    0.1993
x2             74.2040       83.4436         -0.9872     1.0623    0.1589
         eCDF Max
distance   0.7901
x1         0.5562
x2         0.3919

Summary of Balance for Matched Data:
         Means Treated Means Control Std. Mean Diff. Var. Ratio eCDF Mean
distance        0.4976        0.4769          0.0797     1.0914    0.0117
x1             21.8246       21.0965          0.2378     1.3718    0.0318
x2             80.3246       78.9123          0.1509     1.0908    0.0313
         eCDF Max Std. Pair Dist.
distance    0.114          0.0802
x1          0.114          0.5186
x2          0.114          0.5539

Sample Sizes:
          Control Treated
All           647     353
Matched       114     114
Unmatched     533     239
Discarded       0       0
plot(m8.ps)

plot(m8.ps, type="jitter")

To identify the units, use first mouse button; to stop, use second.
plot(m8.ps, type="hist")

m8.data <- match.data(m8.ps)
m8.data.control <- match.data(m8.ps,"control")
m8.data.treat <- match.data(m8.ps,"treat")
m8.ps$match.matrix
     [,1] 
3    NA   
5    NA   
10   "274"
11   "111"
16   NA   
17   NA   
18   "401"
21   NA   
23   "443"
25   NA   
29   NA   
31   "133"
33   NA   
35   NA   
47   NA   
51   "845"
55   "905"
60   NA   
61   NA   
63   NA   
64   NA   
66   "159"
67   NA   
73   "797"
74   "50" 
75   "105"
77   NA   
79   NA   
81   "939"
84   NA   
85   NA   
88   "718"
89   "262"
90   "802"
92   "377"
96   NA   
97   NA   
99   NA   
100  "529"
109  NA   
112  "150"
113  "927"
114  "169"
115  "193"
116  NA   
117  NA   
118  "59" 
119  NA   
120  NA   
123  "907"
126  NA   
130  NA   
139  NA   
140  NA   
142  NA   
154  NA   
155  NA   
156  NA   
163  NA   
164  NA   
166  NA   
167  NA   
168  "355"
174  "978"
177  NA   
184  "415"
185  NA   
189  NA   
192  NA   
194  NA   
196  "883"
198  NA   
205  NA   
213  NA   
215  NA   
216  NA   
217  "72" 
219  NA   
220  NA   
221  "490"
222  NA   
223  NA   
227  "979"
230  NA   
231  "46" 
236  NA   
237  NA   
238  NA   
241  NA   
242  NA   
246  NA   
247  NA   
249  NA   
250  "264"
255  NA   
256  "815"
269  NA   
271  "460"
278  "27" 
284  NA   
286  NA   
289  "847"
290  "248"
291  NA   
293  NA   
297  "684"
304  NA   
305  "138"
306  NA   
309  "545"
310  NA   
311  "572"
313  NA   
315  "754"
318  "554"
321  NA   
324  NA   
343  NA   
347  NA   
348  NA   
351  "12" 
354  NA   
357  NA   
359  NA   
362  NA   
364  "618"
367  NA   
369  NA   
373  "344"
378  "268"
379  NA   
382  NA   
387  NA   
392  NA   
394  NA   
395  NA   
399  NA   
402  "127"
403  "579"
405  NA   
406  NA   
409  NA   
411  "891"
413  "801"
414  NA   
421  NA   
422  "602"
427  "423"
428  "260"
429  NA   
430  "197"
435  "731"
436  "2"  
437  NA   
438  NA   
441  NA   
444  NA   
446  NA   
447  NA   
450  "568"
455  NA   
461  NA   
464  NA   
465  "982"
466  NA   
468  NA   
470  "316"
471  "990"
472  "272"
473  NA   
477  "69" 
480  NA   
483  NA   
484  "203"
485  "994"
487  "245"
491  "856"
494  "141"
504  NA   
506  NA   
508  "857"
509  NA   
516  "719"
517  NA   
521  NA   
523  NA   
525  "641"
527  NA   
537  NA   
538  NA   
540  NA   
543  NA   
544  NA   
548  NA   
550  NA   
553  NA   
558  NA   
559  NA   
560  NA   
561  NA   
569  "353"
570  NA   
577  NA   
578  NA   
582  NA   
584  NA   
588  NA   
594  NA   
597  NA   
598  NA   
600  NA   
601  NA   
605  NA   
606  NA   
609  NA   
610  NA   
611  NA   
615  NA   
619  NA   
620  "121"
628  NA   
631  "265"
635  NA   
636  NA   
638  "968"
640  "955"
643  "535"
644  NA   
645  NA   
647  "182"
652  NA   
654  "70" 
655  "986"
657  NA   
658  NA   
660  NA   
662  NA   
663  "630"
664  NA   
665  NA   
666  "146"
668  "78" 
669  NA   
671  NA   
674  "336"
675  "252"
676  NA   
680  "536"
682  NA   
683  NA   
685  NA   
686  NA   
689  NA   
692  NA   
693  NA   
694  "39" 
700  NA   
715  NA   
716  NA   
717  "161"
723  NA   
730  NA   
733  NA   
734  "456"
739  NA   
741  NA   
745  "621"
746  NA   
747  NA   
748  NA   
753  "844"
758  NA   
759  NA   
761  NA   
769  NA   
771  NA   
777  NA   
778  NA   
781  NA   
783  NA   
787  NA   
792  "410"
796  NA   
799  "573"
803  NA   
807  NA   
811  NA   
814  "749"
817  NA   
819  NA   
821  NA   
824  NA   
827  "622"
832  NA   
834  NA   
836  NA   
837  "32" 
838  NA   
842  NA   
849  NA   
851  "751"
852  NA   
853  NA   
854  "276"
855  NA   
858  NA   
859  "183"
860  "691"
864  "187"
865  NA   
866  "724"
868  NA   
870  "370"
872  NA   
873  "58" 
885  NA   
887  NA   
892  NA   
894  "329"
897  NA   
899  NA   
900  NA   
902  NA   
903  NA   
911  NA   
920  NA   
922  NA   
928  NA   
929  NA   
930  "95" 
931  "358"
932  NA   
938  NA   
941  NA   
943  NA   
944  NA   
945  NA   
946  NA   
948  NA   
950  NA   
951  "40" 
961  NA   
963  "698"
969  NA   
973  "772"
975  "576"
976  "228"
977  "738"
984  NA   
989  NA   
992  "397"
996  NA   
1000 NA   
Pairs <- cbind(Data[row.names(m8.ps$match.matrix),], Data[m8.ps$match.matrix,])
Pairs
             y x1  x2 z          ps        y x1  x2  z          ps
3    10063.205 23  76 1 0.931027491       NA NA  NA NA          NA
5     9705.856 26  70 1 0.999322883       NA NA  NA NA          NA
10    8759.264 20  73 1 0.614433803 3735.166 19  70  0 0.579858911
11    8789.761 20  78 1 0.277876327 3663.815 20  78  0 0.277876327
16    8433.025 23  69 1 0.989968995       NA NA  NA NA          NA
17    8823.235 26  72 1 0.998805205       NA NA  NA NA          NA
18    9172.051 19  76 1 0.200525046 3914.979 23  90  0 0.201613035
21    8189.328 28  74 1 0.999712207       NA NA  NA NA          NA
23    8248.042 23  85 1 0.511189473 4347.073 20  75  0 0.474418575
25    8988.314 24  80 1 0.921447105       NA NA  NA NA          NA
29    8276.923 22  76 1 0.832880575       NA NA  NA NA          NA
31    9489.524 20  78 1 0.277876327 4885.968 20  78  0 0.277876327
33    8236.849 27  68 1 0.999858319       NA NA  NA NA          NA
35    9715.245 23  58 1 0.999555543       NA NA  NA NA          NA
47    8581.192 20  69 1 0.832408685       NA NA  NA NA          NA
51    8121.518 23  82 1 0.710408842 3459.289 20  72  0 0.679220102
55    9021.084 20  72 1 0.679220102 4705.610 17  62  0 0.646344537
60    8619.468 20  70 1 0.788947598       NA NA  NA NA          NA
61    8516.199 26  88 1 0.898562905       NA NA  NA NA          NA
63    9327.283 19  65 1 0.851093425       NA NA  NA NA          NA
64    8694.914 22  74 1 0.897943907       NA NA  NA NA          NA
66    9850.745 22  85 1 0.278556361 4880.289 22  85  0 0.278556361
67    9595.795 19  57 1 0.982308420       NA NA  NA NA          NA
73    9816.380 24  74 1 0.984743618 4546.530 23  75  0 0.947189168
74    8472.126 19  78 1 0.124398661 4816.215 19  78  0 0.124398661
75    9324.843 22  78 1 0.738421072 3529.923 23  82  0 0.710408842
77    8703.039 24  75 1 0.979829980       NA NA  NA NA          NA
79    8760.662 26  63 1 0.999907333       NA NA  NA NA          NA
81    9699.242 19  73 1 0.370421056 3637.931 25  94  0 0.372793394
84    9117.942 31  91 1 0.998186622       NA NA  NA NA          NA
85    9459.019 22  70 1 0.964817558       NA NA  NA NA          NA
88    9524.842 20  75 1 0.474418575 4572.975 19  72  0 0.438756765
89    8576.767 30 105 1 0.791753158 4752.035 27  95  0 0.766444950
90    9108.723 19  70 1 0.579858911 4561.407 18  67  0 0.544482128
92    8301.088 24  85 1 0.739074650 4913.931 24  85  0 0.739074650
96    8781.966 22  65 1 0.991271548       NA NA  NA NA          NA
97    8190.420 25  83 1 0.931244634       NA NA  NA NA          NA
99    8350.664 31  92 1 0.997591998       NA NA  NA NA          NA
100   8893.035 21  74 1 0.764621449 4076.043 24  85  0 0.739074650
109   8710.371 23  76 1 0.931027491       NA NA  NA NA          NA
112   9323.273 21  77 1 0.580683696 3597.790 20  74  0 0.545321906
113   8983.719 24  82 1 0.869184755 4567.696 22  76  0 0.832880575
114   9217.271 20  81 1 0.140925361 4656.117 20  81  0 0.140925361
115   8134.586 21  79 1 0.439590841 4082.801 22  83  0 0.405347997
116   8270.879 24  83 1 0.833351401       NA NA  NA NA          NA
117   9256.702 19  71 1 0.509496988       NA NA  NA NA          NA
118  10052.430 20  76 1 0.404531992 5015.905 20  76  0 0.404531992
119   8729.021 20  70 1 0.788947598       NA NA  NA NA          NA
120   8856.850 22  76 1 0.832880575       NA NA  NA NA          NA
123   9688.339 21  76 1 0.647891157 4807.917 20  73  0 0.614433803
126   9861.592 17  58 1 0.850663742       NA NA  NA NA          NA
130   8684.901 30  74 1 0.999960760       NA NA  NA NA          NA
139   9704.264 21  71 1 0.883992214       NA NA  NA NA          NA
140   8536.793 25  84 1 0.910663678       NA NA  NA NA          NA
142   8156.267 21  67 1 0.959596552       NA NA  NA NA          NA
154   9310.721 19  65 1 0.851093425       NA NA  NA NA          NA
155   8139.426 29  85 1 0.997583850       NA NA  NA NA          NA
156   8773.188 21  71 1 0.883992214       NA NA  NA NA          NA
163   9368.322 29  68 1 0.999980685       NA NA  NA NA          NA
164   9036.764 26  84 1 0.965046737       NA NA  NA NA          NA
166   8996.454 22  68 1 0.979762945       NA NA  NA NA          NA
167   9553.791 23  69 1 0.989968995       NA NA  NA NA          NA
168   8230.864 22  84 1 0.339072068 4157.915 20  77  0 0.338313577
174   9799.736 18  69 1 0.403716516 3653.354 18  69  0 0.403716516
177   8315.752 27  77 1 0.998174321       NA NA  NA NA          NA
184   8937.535 26  93 1 0.681429563 4615.027 25  90  0 0.649434682
185   9649.252 30  96 1 0.980029784       NA NA  NA NA          NA
189  10036.312 25  77 1 0.986759911       NA NA  NA NA          NA
192   9919.054 22  71 1 0.953787482       NA NA  NA NA          NA
194   9054.288 18  50 1 0.993372179       NA NA  NA NA          NA
196   8119.149 21  76 1 0.647891157 4242.838 20  73  0 0.614433803
198   9408.028 22  72 1 0.939516140       NA NA  NA NA          NA
205   9027.826 19  57 1 0.982308420       NA NA  NA NA          NA
213   9896.261 23  66 1 0.995699002       NA NA  NA NA          NA
215   9404.786 25  58 1 0.999939391       NA NA  NA NA          NA
216   9152.874 18  68 1 0.473574259       NA NA  NA NA          NA
217   9070.869 21  78 1 0.510343260 4531.086 20  75  0 0.474418575
219   9536.295 29  77 1 0.999750742       NA NA  NA NA          NA
220   9222.398 28  76 1 0.999492028       NA NA  NA NA          NA
221   9955.165 23  83 1 0.648663308 3427.332 24  87  0 0.616037075
222   8455.751 18  65 1 0.678481820       NA NA  NA NA          NA
223   8476.346 24  77 1 0.964932328       NA NA  NA NA          NA
227   8190.552 24  85 1 0.739074650 3452.033 22  78  0 0.738421072
230   8500.147 23  69 1 0.989968995       NA NA  NA NA          NA
231   8292.887 18  70 1 0.337555917 3769.511 23  88  0 0.308351017
236   8155.931 28  75 1 0.999617645       NA NA  NA NA          NA
237   8361.284 22  69 1 0.973288688       NA NA  NA NA          NA
238   8964.878 25  79 1 0.976859852       NA NA  NA NA          NA
241   8612.428 22  71 1 0.953787482       NA NA  NA NA          NA
242   8626.602 22  55 1 0.999486844       NA NA  NA NA          NA
246   9796.252 22  70 1 0.964817558       NA NA  NA NA          NA
247  10064.063 23  82 1 0.710408842       NA NA  NA NA          NA
249   9443.321 23  69 1 0.989968995       NA NA  NA NA          NA
250   8281.874 22  82 1 0.475263037 3572.118 23  86  0 0.440425259
255   9645.268 26  76 1 0.996285458       NA NA  NA NA          NA
256   8505.833 21  78 1 0.510343260 3457.374 18  68  0 0.473574259
269   9991.929 23  76 1 0.931027491       NA NA  NA NA          NA
271  10052.958 25  85 1 0.884684965 5025.905 21  72  0 0.851522088
278   9414.422 21  82 1 0.250597545 4759.155 21  82  0 0.250597545
284   8439.111 21  50 1 0.999664324       NA NA  NA NA          NA
286  10052.207 25  80 1 0.969485761       NA NA  NA NA          NA
289   8605.068 22  82 1 0.475263037 4699.492 21  79  0 0.439590841
290   8518.714 19  72 1 0.438756765 3637.976 20  76  0 0.404531992
291   9652.115 23  75 1 0.947189168       NA NA  NA NA          NA
293   8206.735 20  75 1 0.474418575       NA NA  NA NA          NA
297   9768.883 19  81 1 0.057107080 4909.346 19  81  0 0.057107080
304   9926.004 21  66 1 0.969284761       NA NA  NA NA          NA
305   8355.090 24  94 1 0.179955228 3446.375 24  94  0 0.179955228
306  10043.549 23  77 1 0.910387791       NA NA  NA NA          NA
309   9232.894 24  86 1 0.680693976 4943.073 21  76  0 0.647891157
310   8609.751 27  69 1 0.999811757       NA NA  NA NA          NA
311   9070.206 21  80 1 0.371211147 4521.036 21  80  0 0.371211147
313   9384.540 22  74 1 0.897943907       NA NA  NA NA          NA
315  10005.416 22  80 1 0.615235752 4266.283 21  77  0 0.580683696
318   8415.244 22  80 1 0.615235752 3356.189 21  77  0 0.580683696
321   9261.289 25  77 1 0.986759911       NA NA  NA NA          NA
324   8160.594 21  78 1 0.510343260       NA NA  NA NA          NA
343   9668.226 24  65 1 0.998801157       NA NA  NA NA          NA
347   9321.374 20  67 1 0.897633155       NA NA  NA NA          NA
348   8914.603 23  74 1 0.959727643       NA NA  NA NA          NA
351   8119.209 19  73 1 0.370421056 3094.405 22  84  0 0.339072068
354   9389.141 22  76 1 0.832880575       NA NA  NA NA          NA
357   9046.107 24  82 1 0.869184755       NA NA  NA NA          NA
359   9942.282 21  53 1 0.999212942       NA NA  NA NA          NA
362   8998.446 23  65 1 0.996759557       NA NA  NA NA          NA
364   8118.007 23  83 1 0.648663308 3285.766 22  80  0 0.615235752
367   9655.120 22  73 1 0.921201637       NA NA  NA NA          NA
369   8536.379 30  86 1 0.998813260       NA NA  NA NA          NA
373   8285.052 22  77 1 0.789510917 4087.288 25  88  0 0.765838210
378   9507.320 22  77 1 0.789510917 4772.660 19  67  0 0.764011430
379   8349.869 24  72 1 0.991300799       NA NA  NA NA          NA
382   9678.451 28  91 1 0.965160787       NA NA  NA NA          NA
387   8202.671 18  57 1 0.953488036       NA NA  NA NA          NA
392   9826.312 21  64 1 0.982367175       NA NA  NA NA          NA
394   9122.539 20  68 1 0.868412737       NA NA  NA NA          NA
395   8441.566 24  62 1 0.999488578       NA NA  NA NA          NA
399   9896.750 23  66 1 0.995699002       NA NA  NA NA          NA
402   9533.508 19  74 1 0.306908446 4950.287 19  74  0 0.306908446
403   8974.255 26  95 1 0.547839674 3474.498 25  92  0 0.512035622
405   8942.022 21  69 1 0.930809713       NA NA  NA NA          NA
406   8747.899 21  70 1 0.910111136       NA NA  NA NA          NA
409   9691.459 21  68 1 0.947019516       NA NA  NA NA          NA
411   8480.075 26 102 1 0.142159789 4174.019 24  95  0 0.141747314
413   8091.298 21  83 1 0.201068490 3132.943 19  76  0 0.200525046
414   8308.879 20  63 1 0.964702426       NA NA  NA NA          NA
421   9261.591 28  62 1 0.999990492       NA NA  NA NA          NA
422   8701.330 23  84 1 0.581508030 4116.149 22  81  0 0.546161426
427   9316.743 20  83 1 0.085018977 3795.357 20  83  0 0.085018977
428   8290.262 23  84 1 0.581508030 4758.149 22  81  0 0.546161426
429   8270.488 28  78 1 0.999103552       NA NA  NA NA          NA
430   9420.592 20  74 1 0.545321906 4441.679 19  71  0 0.509496988
435   9825.739 25  90 1 0.649434682 5082.799 28 101  0 0.617637828
436   9742.111 23  88 1 0.308351017 4625.083 23  88  0 0.308351017
437   8161.450 26  79 1 0.991329954       NA NA  NA NA          NA
438   8454.059 24  67 1 0.997885448       NA NA  NA NA          NA
441   8825.902 25  80 1 0.969485761       NA NA  NA NA          NA
444   8739.745 21  63 1 0.986671133       NA NA  NA NA          NA
446   9319.413 24  71 1 0.993438732       NA NA  NA NA          NA
447   8343.560 25  86 1 0.852376356       NA NA  NA NA          NA
450   9411.461 15  61 1 0.248694489 3795.292 19  75  0 0.249962118
455   9586.175 21  65 1 0.976706259       NA NA  NA NA          NA
461   9748.195 25  78 1 0.982484112       NA NA  NA NA          NA
464   9414.435 19  56 1 0.986626524       NA NA  NA NA          NA
465   9081.892 18  69 1 0.403716516 3832.287 18  69  0 0.403716516
466   9830.065 26  88 1 0.898562905       NA NA  NA NA          NA
468   9725.604 24  78 1 0.953936515       NA NA  NA NA          NA
470   9497.040 23  83 1 0.648663308 4548.612 22  80  0 0.615235752
471  10065.244 25  93 1 0.441260013 4270.356 22  83  0 0.405347997
472   8892.571 22  79 1 0.679957488 4636.373 21  76  0 0.647891157
473   8595.018 23  76 1 0.931027491       NA NA  NA NA          NA
477   9980.913 21  79 1 0.439590841 5082.830 22  83  0 0.405347997
480   9759.734 23  65 1 0.996759557       NA NA  NA NA          NA
483   9931.586 25  80 1 0.969485761       NA NA  NA NA          NA
484   8936.788 22  82 1 0.475263037 4911.846 21  79  0 0.439590841
485   8369.125 19  73 1 0.370421056 3786.049 20  77  0 0.338313577
487   9583.058 22  80 1 0.615235752 3324.102 21  77  0 0.580683696
491   9130.948 25  90 1 0.649434682 5083.920 24  87  0 0.616037075
494   8685.271 18  69 1 0.403716516 3754.009 20  76  0 0.404531992
504   9653.641 20  69 1 0.832408685       NA NA  NA NA          NA
506   9843.296 20  75 1 0.474418575       NA NA  NA NA          NA
508   8113.734 23  80 1 0.812414196 4536.841 22  77  0 0.789510917
509   9578.616 22  62 1 0.996260309       NA NA  NA NA          NA
516   9295.038 27  58 1 0.999991738 4341.911 20  63  0 0.964702426
517   9693.419 30  75 1 0.999947863       NA NA  NA NA          NA
521   9173.679 24  82 1 0.869184755       NA NA  NA NA          NA
523   8827.148 21  68 1 0.947019516       NA NA  NA NA          NA
525   9938.390 20  73 1 0.614433803 3473.282 17  63  0 0.579033680
527   8883.776 19  64 1 0.883644485       NA NA  NA NA          NA
537   8771.457 19  66 1 0.811379847       NA NA  NA NA          NA
538   9316.234 26  80 1 0.988512838       NA NA  NA NA          NA
540   9003.491 24  75 1 0.979829980       NA NA  NA NA          NA
543   8770.785 23  63 1 0.998161937       NA NA  NA NA          NA
544   9698.870 20  60 1 0.984641531       NA NA  NA NA          NA
548   8553.925 27  79 1 0.996781360       NA NA  NA NA          NA
550   8148.534 22  76 1 0.832880575       NA NA  NA NA          NA
553   9122.285 23  74 1 0.959727643       NA NA  NA NA          NA
558   9616.789 24  66 1 0.998407724       NA NA  NA NA          NA
559   9108.177 24  67 1 0.997885448       NA NA  NA NA          NA
560   9289.606 17  57 1 0.883295851       NA NA  NA NA          NA
561   8548.169 24  72 1 0.991300799       NA NA  NA NA          NA
569   8708.500 22  81 1 0.546161426 4619.310 25  92  0 0.512035622
570   8230.249 22  72 1 0.939516140       NA NA  NA NA          NA
577   9275.231 16  58 1 0.677742646       NA NA  NA NA          NA
578   9006.976 23  65 1 0.996759557       NA NA  NA NA          NA
582   8377.612 28  81 1 0.997899691       NA NA  NA NA          NA
584   8877.054 22  75 1 0.868799228       NA NA  NA NA          NA
588   9899.855 25  80 1 0.969485761       NA NA  NA NA          NA
594   8280.168 28  78 1 0.999103552       NA NA  NA NA          NA
597   9666.974 21  60 1 0.994274081       NA NA  NA NA          NA
598   9065.296 22  76 1 0.832880575       NA NA  NA NA          NA
600   9909.194 19  68 1 0.709013494       NA NA  NA NA          NA
601   9711.214 23  64 1 0.997559238       NA NA  NA NA          NA
605   9961.203 20  71 1 0.737766439       NA NA  NA NA          NA
606  10000.974 21  73 1 0.811897568       NA NA  NA NA          NA
609   9846.051 24  75 1 0.979829980       NA NA  NA NA          NA
610   9010.990 26  69 1 0.999490306       NA NA  NA NA          NA
611   9043.765 22  68 1 0.979762945       NA NA  NA NA          NA
615   9667.326 24  68 1 0.997192344       NA NA  NA NA          NA
619   8619.818 27  85 1 0.982542294       NA NA  NA NA          NA
620   8611.190 22  82 1 0.475263037 3782.931 21  79  0 0.439590841
628   9535.096 24  65 1 0.998801157       NA NA  NA NA          NA
631   8996.625 21  83 1 0.201068490 4103.937 19  76  0 0.200525046
635   8411.801 24  58 1 0.999835857       NA NA  NA NA          NA
636   9844.647 22  73 1 0.921201637       NA NA  NA NA          NA
638   9692.800 22  82 1 0.475263037 3708.935 19  72  0 0.438756765
640   9759.973 21  80 1 0.371211147 3263.481 21  80  0 0.371211147
643   9341.530 25  90 1 0.649434682 3392.080 24  87  0 0.616037075
644   9097.679 20  71 1 0.737766439       NA NA  NA NA          NA
645   8961.481 23  72 1 0.976783179       NA NA  NA NA          NA
647   9524.166 18  71 1 0.277197315 4654.608 18  71  0 0.277197315
652   8677.993 21  71 1 0.883992214       NA NA  NA NA          NA
654   8138.474 20  73 1 0.614433803 3336.727 17  63  0 0.579033680
655   9844.808 22  85 1 0.278556361 3364.974 22  85  0 0.278556361
657   8510.441 22  67 1 0.984692658       NA NA  NA NA          NA
658   9221.766 24  77 1 0.964932328       NA NA  NA NA          NA
660   9356.284 24  67 1 0.997885448       NA NA  NA NA          NA
662   9836.159 26  83 1 0.973464204       NA NA  NA NA          NA
663   9888.191 18  77 1 0.065154678 4115.816 18  77  0 0.065154678
664   9360.120 24  74 1 0.984743618       NA NA  NA NA          NA
665   8431.482 26  59 1 0.999970267       NA NA  NA NA          NA
666   9425.583 20  74 1 0.545321906 3087.984 19  71  0 0.509496988
668   9045.037 23  83 1 0.648663308 5026.756 22  80  0 0.615235752
669   9714.318 30  85 1 0.999106580       NA NA  NA NA          NA
671   9902.385 22  59 1 0.998402331       NA NA  NA NA          NA
674   8772.066 21  80 1 0.371211147 3517.968 23  87  0 0.372001927
675   9779.431 21  81 1 0.307629262 3257.432 21  81  0 0.307629262
676   9123.872 26  68 1 0.999616348       NA NA  NA NA          NA
680   9118.848 22  81 1 0.546161426 4174.790 21  78  0 0.510343260
682   9877.023 21  73 1 0.811897568       NA NA  NA NA          NA
683   9758.971 23  79 1 0.851949731       NA NA  NA NA          NA
685   8318.104 28  84 1 0.995087087       NA NA  NA NA          NA
686   8834.475 22  74 1 0.897943907       NA NA  NA NA          NA
689   9092.217 20  62 1 0.973200507       NA NA  NA NA          NA
692   8209.204 24  73 1 0.988474321       NA NA  NA NA          NA
693   8207.055 27  72 1 0.999558541       NA NA  NA NA          NA
694   9214.067 20  74 1 0.545321906 3617.278 19  71  0 0.509496988
700   8857.915 19  51 1 0.996737608       NA NA  NA NA          NA
715   9907.322 21  67 1 0.959596552       NA NA  NA NA          NA
716   9327.662 15  52 1 0.810341127       NA NA  NA NA          NA
717  10086.969 25  81 1 0.959858326 4480.375 22  73  0 0.921201637
723   9530.951 25  69 1 0.998620689       NA NA  NA NA          NA
730   9008.398 22  68 1 0.979762945       NA NA  NA NA          NA
733   9501.549 25  83 1 0.931244634       NA NA  NA NA          NA
734  10003.496 22  84 1 0.339072068 3382.339 23  88  0 0.308351017
739   9935.454 20  63 1 0.964702426       NA NA  NA NA          NA
741   9356.085 19  58 1 0.976629089       NA NA  NA NA          NA
745   8291.639 24  85 1 0.739074650 4517.031 22  78  0 0.738421072
746   9058.627 22  71 1 0.953787482       NA NA  NA NA          NA
747   8923.276 19  70 1 0.579858911       NA NA  NA NA          NA
748   9117.954 25  65 1 0.999557044       NA NA  NA NA          NA
753  10026.682 21  76 1 0.647891157 3918.885 18  66  0 0.613631233
758   8739.011 25  83 1 0.931244634       NA NA  NA NA          NA
759   8607.717 21  65 1 0.976706259       NA NA  NA NA          NA
761   8737.445 25  73 1 0.995713480       NA NA  NA NA          NA
769   8157.387 22  71 1 0.953787482       NA NA  NA NA          NA
771   9327.811 22  66 1 0.988435676       NA NA  NA NA          NA
777   9042.511 21  69 1 0.930809713       NA NA  NA NA          NA
778   9145.595 20  71 1 0.737766439       NA NA  NA NA          NA
781   9431.008 19  65 1 0.851093425       NA NA  NA NA          NA
783   9789.438 29  66 1 0.999989059       NA NA  NA NA          NA
787  10033.700 25  77 1 0.986759911       NA NA  NA NA          NA
792   9501.017 17  82 1 0.006175169 4769.599 17  82  0 0.006175169
796   8596.839 19  68 1 0.709013494       NA NA  NA NA          NA
799   8731.523 19  75 1 0.249962118 3223.524 19  75  0 0.249962118
803   9509.512 24  74 1 0.984743618       NA NA  NA NA          NA
807   9652.646 22  70 1 0.964817558       NA NA  NA NA          NA
811   8628.473 21  55 1 0.998611329       NA NA  NA NA          NA
814   9375.139 23  92 1 0.125138262 3901.443 21  85  0 0.124767992
817   9415.824 26  63 1 0.999907333       NA NA  NA NA          NA
819   9477.929 26  70 1 0.999322883       NA NA  NA NA          NA
821   8164.909 19  59 1 0.969183780       NA NA  NA NA          NA
824   9830.793 26  75 1 0.997201809       NA NA  NA NA          NA
827   9303.990 24  92 1 0.279237416 3489.379 24  92  0 0.279237416
832   9219.476 21  67 1 0.959596552       NA NA  NA NA          NA
834   9312.676 25  79 1 0.976859852       NA NA  NA NA          NA
836   9510.294 25  82 1 0.947358307       NA NA  NA NA          NA
837   9548.625 21  83 1 0.201068490 4959.721 23  90  0 0.201613035
838   9994.571 21  68 1 0.947019516       NA NA  NA NA          NA
842   8812.415 27  83 1 0.990036029       NA NA  NA NA          NA
849  10061.063 22  66 1 0.988435676       NA NA  NA NA          NA
851  10073.666 19  73 1 0.370421056 4337.673 20  77  0 0.338313577
852   8418.042 22  76 1 0.832880575       NA NA  NA NA          NA
853   9900.234 28  82 1 0.997211243       NA NA  NA NA          NA
854   8962.587 27  94 1 0.813444176 3766.032 24  84  0 0.790073132
855   8990.795 23  76 1 0.931027491       NA NA  NA NA          NA
858   8155.517 25  62 1 0.999811119       NA NA  NA NA          NA
859   9146.016 21  76 1 0.647891157 3195.390 18  66  0 0.613631233
860   8426.751 18  71 1 0.277197315 4447.631 18  71  0 0.277197315
864  10063.369 29  99 1 0.885374115 3831.602 27  93  0 0.852801965
865   9840.049 26  86 1 0.939899867       NA NA  NA NA          NA
866   8696.431 31  67 1 0.999998018 5050.338 26  78  0 0.993460769
868   9050.921 21  76 1 0.647891157       NA NA  NA NA          NA
870  10012.378 22  78 1 0.738421072 4844.151 21  75  0 0.709711664
872   9579.439 21  69 1 0.930809713       NA NA  NA NA          NA
873   8431.956 27  99 1 0.512881702 4531.060 22  82  0 0.475263037
885   8343.694 22  71 1 0.953787482       NA NA  NA NA          NA
887   9919.208 19  55 1 0.989901514       NA NA  NA NA          NA
892   8148.956 26  82 1 0.979896798       NA NA  NA NA          NA
894   8118.491 22  81 1 0.546161426 3370.383 19  71  0 0.509496988
897   9312.310 23  64 1 0.997559238       NA NA  NA NA          NA
899   9182.428 21  73 1 0.811897568       NA NA  NA NA          NA
900   8873.222 22  68 1 0.979762945       NA NA  NA NA          NA
902   8817.309 20  75 1 0.474418575       NA NA  NA NA          NA
903   8631.704 22  69 1 0.973288688       NA NA  NA NA          NA
911   9577.510 29  81 1 0.999223524       NA NA  NA NA          NA
920   8367.827 27  65 1 0.999939596       NA NA  NA NA          NA
922   9301.979 27  77 1 0.998174321       NA NA  NA NA          NA
928   8924.814 27  83 1 0.990036029       NA NA  NA NA          NA
929   9071.670 27  75 1 0.998965063       NA NA  NA NA          NA
930   9060.541 21  81 1 0.307629262 3743.188 21  81  0 0.307629262
931   8129.692 22  78 1 0.738421072 3688.849 21  75  0 0.709711664
932   8139.725 22  66 1 0.988435676       NA NA  NA NA          NA
938   9330.340 28  68 1 0.999947686       NA NA  NA NA          NA
941   9781.638 26  82 1 0.979896798       NA NA  NA NA          NA
943   9010.214 26  85 1 0.954085092       NA NA  NA NA          NA
944   9845.467 16  59 1 0.612828045       NA NA  NA NA          NA
945   9292.751 22  58 1 0.998797095       NA NA  NA NA          NA
946   9879.860 27  77 1 0.998174321       NA NA  NA NA          NA
948   9557.862 22  71 1 0.953787482       NA NA  NA NA          NA
950   8701.499 25  79 1 0.976859852       NA NA  NA NA          NA
951   8474.594 20  72 1 0.679220102 3778.927 17  62  0 0.646344537
961  10066.037 21  71 1 0.883992214       NA NA  NA NA          NA
963   8558.791 29 105 1 0.583978287 3784.042 24  88  0 0.547000683
969   9436.242 26  87 1 0.921691872       NA NA  NA NA          NA
973   8728.427 14  71 1 0.007075591 4130.988 14  71  0 0.007075591
975   8984.511 20  82 1 0.109893723 4466.576 20  82  0 0.109893723
976   9987.146 28  59 1 0.999995947 3414.553 25  78  0 0.982484112
977   9932.142 23  84 1 0.581508030 4323.322 20  74  0 0.545321906
984   8939.801 22  75 1 0.868799228       NA NA  NA NA          NA
989   9415.052 22  70 1 0.964817558       NA NA  NA NA          NA
992  10040.653 22  92 1 0.050161420 4917.363 22  92  0 0.050161420
996   9246.277 23  68 1 0.992431736       NA NA  NA NA          NA
1000 10042.248 28  65 1 0.999977698       NA NA  NA NA          NA

Finally, with the matched data, we estimate the average treatment effects, via automatic simulation, with the Zelig package.

# Treatment Effects
z1.ps <- lm(y ~ z + x1 + x2, data = m8.data)
summary(z1.ps)

Call:
lm(formula = y ~ z + x1 + x2, data = m8.data)

Residuals:
     Min       1Q   Median       3Q      Max 
-1034.52  -560.36    14.86   513.64   988.72 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept) 4055.641    404.620  10.023   <2e-16 ***
z           4966.688     81.953  60.604   <2e-16 ***
x1             8.954     21.329   0.420    0.675    
x2            -1.473      6.959  -0.212    0.833    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 612.9 on 224 degrees of freedom
Multiple R-squared:  0.9436,    Adjusted R-squared:  0.9429 
F-statistic:  1250 on 3 and 224 DF,  p-value: < 2.2e-16
x <- transform(m8.data, z = 0)
x1 <- transform(m8.data, z = 1)
s.out <- mean(predict(z1.ps, newdata = x1) - predict(z1.ps, newdata = x))
s.out
[1] 4966.688
barplot(s.out, main = "Estimated average treatment effect")

Zelig package also allows to estimate the effect on the treated, and the effect on the controls.

# Average Treatment Effect on the Controls
z1c.ps <- lm(y ~ x1 + x2, data = m8.data.control)
summary(z1c.ps)

Call:
lm(formula = y ~ x1 + x2, data = m8.data.control)

Residuals:
     Min       1Q   Median       3Q      Max 
-1054.58  -497.42    27.01   505.60   934.99 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept)  3691.38     558.52   6.609  1.4e-09 ***
x1             16.45      40.63   0.405    0.686    
x2              1.14      12.45   0.092    0.927    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 594.8 on 111 degrees of freedom
Multiple R-squared:  0.006571,  Adjusted R-squared:  -0.01133 
F-statistic: 0.3671 on 2 and 111 DF,  p-value: 0.6936
x.out1 <- predict(z1c.ps, newdata = m8.data.treat)
s.out1 <- mean(m8.data.treat$y - x.out1)
s.out1
[1] 4957.543
barplot(s.out1, main = "Estimated effect on the treated")

# Average Treatment Effect on the Treated
z1t.ps <- lm(y ~ x1 + x2, data = m8.data.treat)
summary(z1t.ps)

Call:
lm(formula = y ~ x1 + x2, data = m8.data.treat)

Residuals:
     Min       1Q   Median       3Q      Max 
-1003.19  -526.38   -27.49   549.61  1022.52 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept) 9383.959    595.461  15.759   <2e-16 ***
x1             3.593     25.826   0.139    0.890    
x2            -4.518      8.871  -0.509    0.612    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 633.7 on 111 degrees of freedom
Multiple R-squared:  0.002691,  Adjusted R-squared:  -0.01528 
F-statistic: 0.1498 on 2 and 111 DF,  p-value: 0.8611
x.out2 <- predict(z1t.ps, newdata = m8.data.control)
s.out2 <- mean(x.out2 - m8.data.control$y)
s.out2
[1] 4974.892
barplot(s.out2, main = "Estimated effect on the controls")

I hope that you found this post valuable. Feel free to reproduce the code wherever you want.