Warning message in -mundlak- command running output and Correlated Random Estimator
Dear Stata Users，
I have been analysed a panel data (panel id is scountry, and timevar is year), and run a mundlak model. In my regress equation, I add a variable named sregion which is generated by -sencode region-. And as regard to region, it is a cluster variable that indexs groups of Asian countries (i.e. scountry). So in the fixed effects model, I dropped sregion in equation, and in the mundlak model, I add sregion in the same way as I do in the random effects model & pooled OLS model. However, when I run mundlak command, it gives me some warning message such as:
I wonder if there's wrong in my model specification, and what's the implication these warning message suggests? Thank You.
The Stata codes and dataex code (for saving space, I run -sample 20- before runing -dataex-) that I used is posted as belows:
I have been analysed a panel data (panel id is scountry, and timevar is year), and run a mundlak model. In my regress equation, I add a variable named sregion which is generated by -sencode region-. And as regard to region, it is a cluster variable that indexs groups of Asian countries (i.e. scountry). So in the fixed effects model, I dropped sregion in equation, and in the mundlak model, I add sregion in the same way as I do in the random effects model & pooled OLS model. However, when I run mundlak command, it gives me some warning message such as:
The variable _Isregion_2 does not vary sufficiently within groups and will not be used to create additional regressors.
0% of the total variance in _Isregion_2 is within groups.
0% of the total variance in _Isregion_2 is within groups.
The Stata codes and dataex code (for saving space, I run -sample 20- before runing -dataex-) that I used is posted as belows:
Code:
/*sencode region, gen(sregion) replace sregion=6 if scountry==35 label define sregion 6 以色列, modify tabulate sregion order sregion, after(region)*/ xtset scountry year global indepent "d1 d9 d10 d20 d23 d31 d48 d54 d57 d62 d64 d127" global region "i.sregion" qui regress d65 $indepent $region i.year /*Pooled OLS*/ est store ols qui xtreg d65 $indepent $region i.year, re theta /*Random effects*/ est store re qui xtreg d65 $indepent i.year, fe /*Fixed effects*/ est store fe qui xi: mundlak d65 $indepent $region i.year, full /*mundlak (CRE)*/ est store mundlak esttab ols re fe mundlak, type mtitles nonumber nobase /// label order(d9 d10 d48 d54 d57 d20 d23 d64 d1 d62 d31 d127)
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input double(d65 d1 d9 d10 d20 d23 d31 d48 d54 d57 d62 d64 d127) int year byte sregion str12 region int scountry str38 country
. 34.89032516 39.20000076 43.80704117 5.471628807 2.27748e+11 . 29.8830511 21.8102169 1178.798111 48.63196073 1.998562594 . 2016 3 "南亚" 21 "巴基斯坦"
. 30.20168395 56.40000153 65.73433685 10.5500091 45187272895 5 65.27524069 59.37364197 907.3623858 51.192566 .646530397 6 2009 2 "东南亚" 10 "缅甸"
22.41332054 35.42946884 40.79999924 45.69901657 7.499999169 6514177191 4 64.3864805 36.39899826 814.7750688 49.64191035 2.265771146 7 2012 4 "中亚" 26 "塔吉克斯坦"
. 24.07888883 31.39999962 36.00246811 2.479843833 1.2722e+11 5 57.89985732 26.80417824 47965.00883 41.69339463 5.778846676 7 2008 5 "西亚" 39 "科威特"
34.84011078 34.9402262 41.59999847 47.74212265 5.426673849 3205083428 4 74.63532006 40.82482147 654.3123118 50.55611803 1.191125924 7 2000 4 "中亚" 25 "吉尔吉斯斯坦"
. 40.57102102 25.89999962 26.71323776 -28.09683489 20780222150 6 8.916653069 4.975823402 772.0338215 49.4708559 2.520254045 6 2015 5 "西亚" 42 "也门"
65.84654999 27.42641014 44.70000076 50.75773239 4.65783121 2.44491e+11 6 82.01511646 48.55205536 31482.99716 50.57282027 1.848077862 6 2011 6 "西亚" 35 "以色列"
. 29.2072444 32.59999847 42.17597198 10.5999992 15979538495 4 85.92998111 42.67481613 1955.41315 50.97484407 .746173583 7 2002 5 "西亚" 45 "阿塞拜疆"
25.26073074 30.22564959 35.79999924 42.7291832 -5.962310691 4.89871e+11 5 37.45380194 28.19737816 7631.403183 50.75978161 1.493147245 6 2001 5 "西亚" 46 "土耳其"
. 17.65175242 43 41.5090332 3.237980767 4.06424e+11 . 78.30184656 33.88728333 5901.884123 51.20385004 .299465512 . 2016 2 "东南亚" 11 "泰国"
. 16.94795438 34.29999924 36.82413101 6.224417276 2.51138e+11 6 74.92665943 35.52640152 48447.68058 50.66778104 2.084902456 4 2011 2 "东南亚" 14 "新加坡"
16.97945023 26.30624433 36.59999847 42.26324081 -1.764535541 13360145141 6 75.33514525 37.41130066 34812.71469 48.4369585 1.184773447 7 2009 2 "东南亚" 13 "文莱"
48.56230927 27.96692965 13.30000019 18.23069763 5.411444902 6.12452e+11 6 26.41798876 8.706881523 21056.34715 43.66498573 2.959993577 6 2012 5 "西亚" 36 "沙特阿拉伯"
30.27387047 29.51941619 37.40000153 41.90572357 9.427665099 2.36695e+11 6 56.89803451 33.96840286 8889.684192 48.63004175 1.827924244 7 2007 2 "东南亚" 12 "马来西亚"
. 32.60738298 35.79999924 44.52225494 13.04036341 13789041601 3 69.79820735 34.80432129 2900.122554 50.80840895 1.083596746 7 2005 4 "中亚" 28 "土库曼斯坦"
. 13.65049428 25.39999962 31.53526306 2.82772231 1.30466e+12 6 71.40522278 34.80347061 25458.88701 49.95375544 .451318044 6 2016 1 "东亚" 4 "韩国"
. 28.89285636 20.5 37.78887939 4.452694304 48734720416 6 34.79077946 22.78753471 18302.31933 42.29722457 3.041590016 6 2007 5 "西亚" 41 "阿曼"
. 23.38538171 32.59999847 34.29017258 -2.465514923 13301457646 6 78.85535903 30.60792732 31430.96259 48.51167901 1.345029067 7 2016 2 "东南亚" 13 "文莱"
22.79460907 24.19079855 42.29999924 43.40007782 6.468567672 20889606053 6 46.17306941 25.83148575 21796.01514 39.27042119 7.49936409 6 2006 5 "西亚" 37 "巴林"
43.39176941 17.68559336 47.79999924 48.8276825 6.900204817 8.9083e+12 6 81.35362609 47.27745056 6496.624013 48.47922338 .508136747 6 2015 1 "东亚" 1 "中国"
. 41.08355939 19.29999924 34.22161865 6.572160298 1.80886e+11 6 24.7269512 14.18980789 5338.521985 49.42231449 3.320373173 6 2013 5 "西亚" 30 "伊拉克"
. 49.91039203 29.79999924 36.44207764 -2.216748768 557858287.5 6 48.86463414 28.26400185 580.5871118 49.29390717 3.92977311 6 2003 2 "东南亚" 16 "东帝汶"
38.81483078 37.54935769 19.29999924 27.64243507 8.093331161 21109859431 6 18.72712403 9.961771965 3557.302686 48.51135674 3.779888824 6 2006 5 "西亚" 33 "约旦"
6.130790234 36.05120025 54.59999847 48.37291718 3.83312394 73115059421 5 31.45765519 21.92624664 535.2467234 48.98478537 1.842264814 7 2002 3 "南亚" 19 "孟加拉国"
44.25460815 19.70270661 22.89999962 38.43492508 3.600000001 11123101342 4 73.38426513 33.49477386 3827.343195 53.04946153 .438331527 8 2014 5 "西亚" 44 "亚美尼亚"
14.87967968 30.6862231 45.20000076 55.30569077 4.920067747 4.53414e+11 6 59.72376797 43.46536636 2143.38989 49.95361052 1.393740137 6 2000 2 "东南亚" 15 "印度尼西亚"
41.31546021 28.82538507 12.89999962 18.15807152 9.996857794 5.81011e+11 6 25.9677462 7.88995409 20575.49795 43.75573894 2.918964195 6 2011 5 "西亚" 36 "沙特阿拉伯"
39.52645874 20.49701576 42.5 42.03935242 5.416503715 28675502255 6 49.90176138 25.94435883 21799.65217 38.24893551 1.161799071 6 2013 5 "西亚" 37 "巴林"
. 41.09862757 35.70000076 41.25873184 4.260088012 1.17555e+11 5 19.17766824 10.3189888 848.6317831 48.40496243 2.276383384 7 2000 3 "南亚" 21 "巴基斯坦"
. 19.92410506 35.20000076 39.21260834 4.435328147 1.44978e+11 6 67.32487171 38.35535812 35233.13448 50.24136979 -1.474532842 4 2003 2 "东南亚" 14 "新加坡"
10.45038033 44.40866777 26.20000076 31.39019775 3.338427956 26655991280 6 17.96740838 12.1818161 1225.472386 49.475287 2.754970495 6 2007 5 "西亚" 42 "也门"
19.36459923 24.61826181 31.20000076 35.99262619 25.04899952 41629404407 4 96.60252512 39.29629517 4851.176909 50.60749887 1.133855466 7 2007 5 "西亚" 45 "阿塞拜疆"
. 30.09215844 51 54.52573395 26.11149322 2205437294 7 69.38097978 47.23474503 6622.934816 46.85813257 3.670136685 5 2006 3 "南亚" 23 "马尔代夫"
. 31.56230789 48.20000076 52.08727264 -13.12905331 1748799604 7 66.62352167 44.22310638 5447.973844 47.29024488 2.843793532 5 2005 3 "南亚" 23 "马尔代夫"
2.686769962 43.3723428 67.80000305 70.4662323 5.798782326 3582186705 5 97.48349375 77.03759003 672.1678299 50.14457814 1.665414155 6 2000 2 "东南亚" 8 "老挝"
. 13.8818369 65.90000153 66.77802277 2.223120972 1.70663e+11 . 61.61430116 40.50164032 66410.75647 24.76612002 3.495069918 . 2016 5 "西亚" 38 "卡塔尔"
41.25574875 21.38245749 23.29999924 32.12342453 5.473838085 7017851503 4 75.06078393 24.80539894 1610.707253 52.67983401 -.672509797 7 2002 5 "西亚" 43 "格鲁吉亚"
9.412480354 31.65717891 64.90000153 66.45968628 6.787316408 61146300623 5 89.07007874 65.55615234 787.6541509 50.73659132 1.341154893 7 2000 2 "东南亚" 7 "越南"
28.89488029 35.1680164 40.29999924 46.40288162 6.900001455 8458800788 4 62.31972732 36.00566101 968.3856026 49.75500149 2.155884123 7 2016 4 "中亚" 26 "塔吉克斯坦"
38.48477173 23.99065262 23.79999924 29.86307907 .815560066 42069990678 6 32.35572802 17.87960052 7189.633711 49.7685546 4.334248771 6 2015 5 "西亚" 34 "黎巴嫩"
67.79532623 27.57060723 43.70000076 49.69804382 1.942507688 2.4924e+11 6 83.49418249 48.73854446 31507.47856 50.53414008 1.846151321 6 2012 6 "西亚" 35 "以色列"
56.79785156 27.99003411 42.79999924 54.11386108 .161829705 1.7413e+11 6 77.73611843 50.53398895 26503.84335 50.70740534 2.014058394 6 2002 6 "西亚" 35 "以色列"
39.008461 23.38376014 49.5 53.78780365 3.444243766 2.25211e+11 6 79.9113472 47.37327194 3544.208344 50.65981599 .925373854 6 2001 2 "东南亚" 11 "泰国"
10.38358974 38.60680553 72.5 76.57480621 3.411560276 13764950914 5 90.22976431 75.25361633 525.0822526 50.68553296 1.051592684 7 2007 3 "南亚" 17 "尼泊尔"
10.35523033 35.20459699 39.09999847 41.44550323 4.674707981 2.06178e+11 5 28.65220851 20.060606 1111.195962 48.62573869 2.087792429 7 2014 3 "南亚" 21 "巴基斯坦"
9.664879799 46.37784615 25.60000038 33.25062561 3.972696401 23678154701 6 21.9923583 14.75080109 1182.89825 49.46921797 2.811704436 6 2004 5 "西亚" 42 "也门"
. 20.35443386 34.20000076 38.5675621 4.211686552 1.38821e+11 6 65.90763057 37.24038315 33242.98633 50.18041925 .912639806 4 2002 2 "东南亚" 14 "新加坡"
27.40694046 32.37845033 42.20000076 43.89268494 5.390988339 1.7217e+11 6 56.95498097 36.74354172 7114.816741 48.9535893 2.087457079 7 2002 2 "东南亚" 12 "马来西亚"
. 23.56789155 23.70000076 30.11450958 2 42911390492 . 32.43324874 17.91213989 7143.959095 49.8212903 2.617573568 . 2016 5 "西亚" 34 "黎巴嫩"
20.4384594 22.56954919 28.5 33.13799667 2.200000188 54102205125 4 90.3379661 32.18070602 5820.079847 50.35660326 1.328763827 7 2012 5 "西亚" 45 "阿塞拜疆"
38.78591156 38.03247889 17.89999962 27.98587608 8.567297894 18058165848 6 17.80541289 9.287888527 3262.190577 48.32748091 2.539769048 6 2004 5 "西亚" 33 "约旦"
4.948019981 41.67513194 65.40000153 68.27448273 6.067002304 4255861752 5 97.51756575 74.10515594 762.7462611 50.32340669 1.487497465 6 2003 2 "东南亚" 8 "老挝"
12.00601959 13.4904529 64.69999695 64.74822998 4.410274619 1.55056e+11 6 59.24820794 36.91139984 68899.48531 24.15723422 6.465722916 6 2013 5 "西亚" 38 "卡塔尔"
42.77283096 24.04661628 23.5 29.47122002 2.002921346 41729660234 6 32.4139545 17.79335022 7447.364344 49.66988068 6.01643946 6 2014 5 "西亚" 34 "黎巴嫩"
15.95436001 26.68595024 36.40000153 42.80954361 -1.939714638 13600124166 6 74.7268861 37.99061203 35860.38878 48.53779891 1.163759826 7 2008 2 "东南亚" 13 "文莱"
5.66012001 36.24181221 75.59999847 78.76286316 10.77108367 9014922681 6 89.3792902 77.39084625 669.0363309 51.44419184 1.527719882 6 2006 2 "东南亚" 9 "柬埔寨"
. 18.54400016 36.40000153 39.53967285 9.111527148 2.02776e+11 6 69.5113648 38.15546417 44191.23809 50.50940997 4.166002864 4 2007 2 "东南亚" 14 "新加坡"
. 30.82856398 37.70000076 47.53282166 6.2 39563379218 4 68.33423798 36.84137726 6986.855946 50.76108928 1.732524453 8 2016 4 "中亚" 28 "土库曼斯坦"
12.69112968 30.64628902 41.59999847 48.71278 2.849421858 11971150348 6 69.8744501 44.02797699 35923.40183 49.36053246 2.108246022 7 2000 2 "东南亚" 13 "文莱"
. 40.53624841 19 33.83166885 11 2.11894e+11 . 24.98377551 13.97342587 5695.679143 49.38655735 2.965163696 . 2016 5 "西亚" 30 "伊拉克"
66.1810379 27.7993142 44.5 49.7779541 3.410136515 2.68335e+11 6 84.90981643 48.60968018 32661.29413 50.44726186 1.919543799 6 2014 6 "西亚" 35 "以色列"
1.256839991 48.09824698 36.79999924 49.50733948 8.444163227 8689883606 6 17.87735492 18.62209892 376.7587142 48.32011929 4.81804112 6 2003 5 "西亚" 29 "阿富汗"
. 48.60179947 28.89999962 36.25760651 6.181915593 20345854642 6 28.53385496 18.85337448 1138.247142 49.42201079 2.817702613 6 2000 5 "西亚" 42 "也门"
43.40129852 28.79957165 23.89999962 30.1530056 3.871259086 22676199979 6 28.93623532 17.74120903 6749.152265 50.17578092 3.77569497 6 2001 5 "西亚" 34 "黎巴嫩"
. 20.29152993 43.09999847 44.91290665 . . . 50.485584 28.70479584 . 37.87034978 3.812796793 . 2016 5 "西亚" 37 "巴林"
. 24.54597519 24 43.56256104 -1.106912723 57992510273 6 35.37992291 23.02961922 17914.02821 38.64086799 6.239210094 6 2011 5 "西亚" 41 "阿曼"
16.60396004 46.19673065 14.5 16.59819984 13.00097752 812196700.7 6 46.86398361 12.0844326 743.7555695 49.23495061 1.282059981 6 2009 2 "东南亚" 16 "东帝汶"
97.97155762 16.66759216 23.70000076 26.22597122 .707509946 1.02773e+12 6 68.17474254 29.30078888 20843.1348 49.88218322 .514682828 6 2009 1 "东亚" 4 "韩国"
. 43.74688158 12.89999962 12.99063492 5.666251557 1192299136 6 47.75520265 9.368288994 939.801679 49.21811634 2.207092325 6 2016 2 "东南亚" 16 "东帝汶"
. 30.60339812 37.5 43.15819168 6.640061263 5.20931e+11 5 36.19489591 27.87056732 8237.342158 50.7527626 1.518095558 6 2000 5 "西亚" 46 "土耳其"
. 37.36404092 19.39999962 28.80459213 . . . 17.19395932 8.332414627 . 49.43376595 -1.638838749 . 2016 5 "西亚" 32 "叙利亚"
. 41.30839983 19.29999924 34.59195328 13.93643017 1.69731e+11 6 24.53475468 14.29857922 5178.422294 49.43559234 3.25442375 . 2012 5 "西亚" 30 "伊拉克"
. 30.17651345 33.09999847 43.84670258 9.9 14448045760 4 83.56604073 43.75944901 1781.246395 51.04925671 .774765939 7 2001 5 "西亚" 45 "阿塞拜疆"
. 48.5695855 43 48.34260559 . . 6 16.7685324 17.11361313 . 48.50645974 3.494658738 6 2000 5 "西亚" 29 "阿富汗"
. 19.53345965 34.90000153 39.1884346 9.549175476 1.58822e+11 6 68.3398714 38.47191238 38117.41053 50.30328063 1.251916673 4 2004 2 "东南亚" 14 "新加坡"
29.75400925 33.90144299 38.5 42.75185776 7.63226759 1.99591e+11 6 63.83260396 33.37248611 2129.499247 49.52359052 1.619573147 4 2010 2 "东南亚" 6 "菲律宾"
. 46.72946174 16.60000038 19.34935379 14.17410714 718751924.6 6 46.78698034 14.0117712 666.6777273 49.25359706 1.226006137 6 2008 2 "东南亚" 16 "东帝汶"
20.93221092 38.44764918 27.89999962 34.17612457 4.999999998 . 4 19.92903021 12.8299408 . 49.0482509 3.334750651 8 2006 5 "西亚" 32 "叙利亚"
25.04660988 32.93579742 43.09999847 44.13132858 .517675306 1.63363e+11 6 57.00631523 37.15282822 6893.280513 49.00911443 2.189718758 7 2001 2 "东南亚" 12 "马来西亚"
11.71901989 33.91610685 75.69999695 78.6882782 .086696959 10609615491 6 91.10463754 77.72267151 752.9779185 51.3194373 1.499446217 6 2009 2 "东南亚" 9 "柬埔寨"
46.91810989 26.29499426 22.39999962 29.01993942 9.349502765 29249087911 6 30.2060149 17.46617126 7157.550781 48.95087988 .715048671 6 2007 5 "西亚" 34 "黎巴嫩"
. 17.77454034 33.70000076 37.02825546 -.603388298 2.05155e+11 6 72.18639869 35.74271011 41133.29981 50.62561424 3.015949915 4 2009 2 "东南亚" 14 "新加坡"
. . . . . . . . . . . . . 2013 5 "西亚" 211 "巴勒斯坦"
25.93504906 36.851618 19.5 29.78403091 . . 4 17.92652511 8.902561188 . 49.54765133 -.739404269 8 2011 5 "西亚" 32 "叙利亚"
5.445340157 37.06057025 56.5 48.94739532 5.293294718 67013463193 5 30.62907821 21.98221588 509.2934347 48.97092327 1.958193767 7 2000 3 "南亚" 19 "孟加拉国"
. 25.59676842 35.29999924 41.70191956 7.6682919 44825899741 5 48.07707745 29.74916267 2296.408798 50.83096744 .755923688 8 2006 3 "南亚" 22 "斯里兰卡"
. 38.79640303 48.70000076 46.89050293 10.72784061 825183060.9 7 81.08867276 46.44882965 1360.792252 48.40039578 2.809384438 6 2002 3 "南亚" 18 "不丹"
49.47153091 28.08857249 48.40000153 58.72792435 8.169051764 1.73805e+11 6 76.40547737 54.48500443 27636.34077 50.72053211 2.642331913 6 2000 6 "西亚" 35 "以色列"
. 25.47001196 43.40000153 50.7262001 9.3 91059947286 4 85.54165611 47.31745529 6107.709259 51.89042723 .336402206 7 2003 4 "中亚" 24 "哈萨克斯坦"
86.49107361 19.78222546 32.09999847 35.15907669 7.432433614 7.97327e+11 6 67.17162109 38.78481674 16734.84566 49.8269756 .577957277 6 2002 1 "东亚" 4 "韩国"
23.94791985 17.84821566 50.29999924 55.61853027 10.63614046 6.10062e+12 6 81.89096156 53.16585541 4560.512586 48.52880233 .482959689 6 2010 1 "东亚" 1 "中国"
. 21.05653111 42.90000153 42.54133224 2.539772469 24645054296 6 49.05079691 25.71962357 20797.00522 37.75765084 6.128062258 6 2009 5 "西亚" 37 "巴林"
. 26.3647743 33.40000153 43.7960701 -1.545408134 33742158886 5 48.39780532 30.83274078 1795.082135 50.22200532 .758307596 8 2001 3 "南亚" 22 "斯里兰卡"
13.90909004 35.41057114 35.40000153 44.67758942 3.999999997 21723230594 4 69.73084209 34.97423172 859.5821277 50.29309682 1.223831519 7 2002 4 "中亚" 27 "乌兹别克斯坦"
35.39751816 27.24247644 36.70000076 41.44643784 5.29391284 2.68517e+11 6 58.72921652 33.07190323 9377.187567 48.41653613 1.842740419 7 2011 2 "东南亚" 12 "马来西亚"
52.74705124 19.00425632 45.90000153 47.34571838 .839959472 3.4397e+11 6 81.45523514 39.21286774 5093.5805 51.02760649 .476955829 6 2011 2 "东南亚" 11 "泰国"
43.9144783 19.46110963 23.29999924 35.67499542 7.200000003 10393595650 4 73.70339215 30.13440323 3606.480554 53.15940744 .220269188 8 2012 5 "西亚" 44 "亚美尼亚"
. 40.25711011 25.89999962 27.08283997 -9.779168417 18748089228 . 8.874673298 4.931006908 679.66736 49.47575622 2.451502043 . 2016 5 "西亚" 42 "也门"
45.57901001 23.70008649 23.10000038 28.18805504 2.804246836 39859470964 6 32.8983813 17.44843292 8107.444173 49.33945731 6.905296367 6 2012 5 "西亚" 34 "黎巴嫩"
13.44079971 29.95621306 42 40.91385269 6.061093054 1.46997e+11 5 39.34417197 22.9413414 922.161128 49.52542005 1.157188028 7 2014 3 "南亚" 19 "孟加拉国"
end
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