Joao Pedro <[email protected]> asks,
> I would like to know if there is any command which would automatically
> generate dummy variables out of a categorical variable. [...]
Yes there is. The command is -tabulate- with the -generate(<varnamestub>)-
option. For instance, typing
. tabulate rep78, gen(rr)
would present a one-way tabulation of categorical variable rep78 *AND* it
would create new 0/1 variables named rr1, rr2, ... Variable rr1 will contain
1 when rep78 contains its first value and 0 when rep78 contains another,
nonmissing value; rr2 will contain 1 when rep78 contains its second value and
0 when rep78 contains another, nonmissing value; and so on. The new variables
will contain . where rep78 contains missing.
Here's an example:
. sysuse auto
(1978 Automobile Data)
. tabulate rep78, gen(rr)
Repair |
Record 1978 | Freq. Percent Cum.
------------+-----------------------------------
1 | 2 2.90 2.90
2 | 8 11.59 14.49
3 | 30 43.48 57.97
4 | 18 26.09 84.06
5 | 11 15.94 100.00
------------+-----------------------------------
Total | 69 100.00
. describe rr*
storage display value
variable name type format label variable label
----------------------------------------------------------------
rr1 byte %8.0g rep78== 1.0000
rr2 byte %8.0g rep78== 2.0000
rr3 byte %8.0g rep78== 3.0000
rr4 byte %8.0g rep78== 4.0000
rr5 byte %8.0g rep78== 5.0000
. summarize rr*
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
rr1 | 69 .0289855 .1689948 0 1
rr2 | 69 .115942 .3225009 0 1
rr3 | 69 .4347826 .4993602 0 1
rr4 | 69 .2608696 .4423259 0 1
rr5 | 69 .1594203 .3687494 0 1
-- Bill
[email protected]
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