7楼是正确的,
. program hausmantest ,eclass
1. tempname b bre bfe
2. xtreg gdp D l fixi t i.city,fe r
3. matrix `bfe'=e(b)
4. xtreg gdp D l fixi t i.city,re r
5. matrix `bre'=e(b)
6. matrix `b'=`bre'-`bfe'
7. ereturn post `b'
8. end
把符号变一下,前边的点是tab上边的点,`', `', `', `'这种组合形式
Bootstrap results Number of obs = 70
Replications = 400