xi:
interactive expansion
use it to create dummy variables from categorical variables
example: . tab sex
Sex | Freq. Percent Cum.
----------+---------------------------------
Male | 154,033 47.69 47.69
Female | 168,958 52.31 100.00
----------+---------------------------------
Total | 322,991 100.00
. xi i.sex i.sex _Isex_1-2 (naturally coded; _Isex_1 omitted)
. des _I*
storage display value
variable name type format label variable label ------------------------------------------------------------------------------- _Isex_2 byte %8.0g sex==2
advanced syntax:
xi: reg lnwage i.sex*edyrs (we will talk about this in lab x)
Categories: Lab2