Dear Statalist,

I have any issue regarding comparing the fixed-effect model and mundlak effect in controlling the means of time-variant variables as additional regressors.
Here are the results. I am wondering why the coefficient of fixed and random effect is slightly different. Might it be due to missing data?

thanks and regards,

PHP Code:
 xtreg lremit $xlist0 i.yearvce(cluster pairidfe

note
comlang_off omitted because of collinearity
note
colony omitted because of collinearity
note
contig omitted because of collinearity

Fixed
-effects (withinregression               Number of obs      =      1102
Group variable
pairid                          Number of groups   =       271

R
-sq:  within  0.1197                         Obs per groupmin =         1
       between 
0.5477                                        avg =       4.1
       overall 
0.5723                                        max =         7

                                                F
(10,270)          =      5.71
corr
(u_iXb)  = 0.0948                         Prob F           =    0.0000

                               
(StdErradjusted for 271 clusters in pairid)
------------------------------------------------------------------------------
             |               
Robust
      lremit 
|      Coef.   StdErr.      t    P>|t|     [95ConfInterval]
-------------+----------------------------------------------------------------
       
lgdpc |   .4199601   .1413403     2.97   0.003      .141691    .6982293
   lgdpc_hos 
|   .2482984   .3412649     0.73   0.467    -.4235802    .9201771
      lcost2 
|  -.1912492   .0978837    -1.95   0.052    -.3839617    .0014632
     lmig_st 
|   .3740764   .1592843     2.35   0.020     .0604792    .6876735
 comlang_off 
|          0  (omitted)
      
colony |          0  (omitted)
      
contig |          0  (omitted)
             |
        
year |
       
2012  |   .0043988   .0190377     0.23   0.817    -.0330823      .04188
       2013  
|  -.0265595   .0471652    -0.56   0.574    -.1194178    .0662988
       2014  
|  -.0332107   .0542274    -0.61   0.541    -.1399731    .0735516
       2015  
|   .1402847    .055213     2.54   0.012     .0315819    .2489875
       2016  
|   .0661839   .0598106     1.11   0.269    -.0515705    .1839384
       2017  
|   .0920051   .0592864     1.55   0.122    -.0247174    .2087276
             
|
       
_cons |  -6.884898   5.217741    -1.32   0.188    -17.15753    3.387733
-------------+----------------------------------------------------------------
     
sigma_u |  1.2156288
     sigma_e 
|  .34090766
         rho 
|  .92708901   (fraction of variance due to u_i)
------------------------------------------------------------------------------ 
Mundlak Effect results

PHP Code:
 xtreg lremit $xlist0 $vlist0 i.yearvce(cluster pairid

Random-effects GLS regression                   Number of obs      =      1102
Group variable
pairid                          Number of groups   =       271

R
-sq:  within  0.1197                         Obs per groupmin =         1
       between 
0.6579                                        avg =       4.1
       overall 
0.6785                                        max =         7

                                                Wald chi2
(17)      =    847.77
corr
(u_iX)   = (assumed)                    Prob chi2        =    0.0000

                                 
(StdErradjusted for 271 clusters in pairid)
--------------------------------------------------------------------------------
               |               
Robust
        lremit 
|      Coef.   StdErr.      z    P>|z|     [95ConfInterval]
---------------+----------------------------------------------------------------
         
lgdpc |   .4439019   .1406352     3.16   0.002     .1682619    .7195418
     lgdpc_hos 
|   .2524156   .3360553     0.75   0.453    -.4062407    .9110718
        lcost2 
|  -.2028169   .0977656    -2.07   0.038    -.3944339   -.0111998
       lmig_st 
|   .3689689   .1583542     2.33   0.020     .0586004    .6793375
   comlang_off 
|   .0681932   .1503237     0.45   0.650    -.2264358    .3628223
        colony 
|   -.135961   .1806898    -0.75   0.452    -.4901066    .2181845
        contig 
|   .0056654   .3514274     0.02   0.987    -.6831196    .6944504
    lgdpc_mean 
|  -.1943218   .1454022    -1.34   0.181    -.4793049    .0906614
lgdpc_hos_mean 
|  -.0928574     .34678    -0.27   0.789    -.7725336    .5868189
   lcost2_mean 
|  -.3658746   .2326023    -1.57   0.116    -.8217667    .0900174
  lmig_st_mean 
|    .399029   .1679837     2.38   0.018     .0697869     .728271
               
|
          
year |
         
2012  |   .0038119   .0192994     0.20   0.843    -.0340142    .0416381
         2013  
|    -.02782   .0471031    -0.59   0.555    -.1201403    .0645004
         2014  
|  -.0348137   .0541059    -0.64   0.520    -.1408593    .0712318
         2015  
|   .1384236   .0552425     2.51   0.012     .0301503     .246697
         2016  
|   .0623224   .0595451     1.05   0.295    -.0543839    .1790286
         2017  
|    .089855   .0592783     1.52   0.130    -.0263284    .2060383
               
|
         
_cons |  -7.467168   .8463628    -8.82   0.000    -9.126009   -5.808328
---------------+----------------------------------------------------------------
       
sigma_u |  1.0303308
       sigma_e 
|  .34090766
           rho 
|  .90132614   (fraction of variance due to u_i)
-------------------------------------------------------------------------------