st: R2 in a regression with time and fixed effects

["andrea carrozzone" <a.carrozzone@libero.it>]

Dear Statalist,
 
I ran a regression (xtreg command) with fixed effects (for 60 groups). I then included time effects by putting a dummy for each year (7 years). I notice that the R2 (overall) decreases hugely. 
 
I wonder if it is reasonable. Does it depend on the way the R2 overall is computed with the xtreg command?
 
Thanks a lot, 
 
Andrea


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