st: why is stata dropping more dummies than necessary

["Indradeep Ghosh" <indradeepg@hotmail.com>]

hi all,
i am running fixed effects panel regressions (country by year by variable), 
but i am using time and country dummies for time and country fixed effects, 
plus a constant, instead of the xtreg command. i have 11 years and 30 
countries - i find that stata drops 1 country dummy but two time dummies - i 
would have expected stata to drop only 1 time dummy. why is stata dropping 
2? am i missing something obvious? this is not a matsize issue, since i set 
a large enough matsize for all my regressions. any help/suggestion will be 
greatly appreciated. many thanks.
deep


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