Hi everyone,

I am running a FE regression with dependent variable = lnyield and the independent variables listed below. These are only some of the observations. The entire database has more than 60000 obs.

lnyield LCC overlap rival postmerger lnpop HHI lnMKS
-.8648053 0 0 1 0 13.670955 8.529709 4.0183864 5932
-1.1476643 0 1 1 0 13.852258 8.231647 3.4807014 5848
-1.219536 0 0 0 1 13.59934 9.2103405 4.6051702 1513
-1.8932327 0 1 1 0 14.771145 8.155919 3.8005126 744
-1.900237 0 0 1 0 15.113273 8.764023 3.158886 5884
-1.54112 0 1 1 0 15.102163 9.193841 -.19235876 3648
-1.36971 0 0 0 1 13.492355 9.2103405 4.6051702 1270
-1.328943 0 0 0 1 13.849359 8.34725 2.2026672 204
-1.1848733 0 0 0 0 12.779123 9.2103405 4.6051702 7572
.2160983 0 0 1 0 14.706728 8.517295 3.92206 7205
-1.9089514 0 0 1 1 14.06381 9.2103405 4.6051702 4536
-.667846 0 0 1 0 12.678886 9.2103405 4.6051702 7569
-.8977488 0 0 1 0 12.61196 9.2103405 4.6051702 7055
-1.351455 0 1 1 1 14.432618 8.186669 3.829272 6707
-.7965 0 0 1 0 13.236973 8.7299 4.3086824 119
-1.621516 0 1 1 1 16.038513 7.887007 3.539664 3702
-2.151268 0 0 1 0 14.778112 8.5967455 3.572692 623
-1.7420292 0 1 1 0 13.479315 9.1810875 4.5904336 3377
.11120303 0 0 0 0 13.178032 9.189557 4.594723 2226
-1.1529104 0 0 0 0 14.194046 9.180557 4.5901647 7565
-1.5734254 0 0 1 1 14.219168 8.256967 3.5404146 6357
-1.7809333 0 0 1 1 13.239158 8.117113 3.4380035 3769
-.6687411 0 0 0 1 13.968255 9.2103405 4.6051702 5679
-2.2370486 0 1 1 0 14.809838 7.85816 -2.2622492 3297
-2.1406624 0 1 1 1 12.877996 8.639835 3.463827 6810
-.24347006 0 0 1 0 14.094083 9.2103405 4.6051702 7540
-2.374856 0 1 1 1 14.771145 8.195097 -.4514865 746
-2.1885011 0 1 1 1 13.868747 8.518848 -.929131 6597
-1.260335 0 0 1 1 15.37245 8.987753 4.490173 4541
-.3013127 0 0 0 1 13.427325 9.2103405 4.6051702 2166
-.05321046 0 0 0 0 12.965796 8.747899 4.3237357 285
-1.1232489 0 1 1 0 13.584218 8.127339 3.376789 438
-.11522526 0 0 0 1 14.690218 8.584178 4.145679 2207
-.6068562 0 0 0 1 13.364743 9.181209 .3762531 3183
-2.3009276 0 0 0 0 11.85454 9.2103405 4.6051702 5574
-1.9705735 0 1 1 1 13.55062 8.510394 .9403883 7497
-.4194473 0 0 0 0 12.456385 8.631491 3.484354 1427
-1.1838019 0 0 0 0 11.279772 9.2103405 4.6051702 6855

When I run the regression, xtreg lnyield postmerger##overlap postmerger##rival HHI lnMKS lnpop LCC i.year_quarter, fe ,Stata omits LCC and lnPop because of collinearity but I can't understand why. If I run the same RE regression none variable is omitted. Do you know why?

Thanks