# st: splitting columns

 From "Katsuhide Isa" <[email protected]> To <[email protected]> Subject st: splitting columns Date Thu, 28 Nov 2002 11:16:36 +0900

```I have a survey data which has the following structure.
Each column contains the result of a survey question

* data1
Q1 Q2 Q3 Q4
1 1 1 …
2 2 2
3 3 12
12 4 1
13 5 1
23 12 2
123 24 1
13 14 2
23 125 12
2 234 1
… … …

In the example above, Q1 has three choices,
Q2 five choices, and Q3 two choice.
But, it should have been typed as below:

* data2
Q1_1 Q1_2 Q1_3 Q2_1 ...
1 0 0 1
0 1 0 0
0 0 1 0
1 1 0 0
1 0 1 0
0 1 1 1
1 1 1 0
1 0 1 1
0 1 1 1
0 1 0 0
… … …
Q1_1 indecates the 1st choice of Q1, Q1_2 the 2nd
choice, and so on.
That is, I'd like each variable to take on one if a
relevant choice is selected.

The question is, is it possible to convert the data1 into
data2 from within Stata?
One immediate solution would be to create new
variables using -generate- as below (in the case of
three choices):

gen Q1_1 = 1 if Q1 == 1 | Q1 == 12 | Q1 == 13 | Q1 == 123
gen Q1_2 = 1 if Q1 == 2 | Q1 == 12 | Q1 == 23 | Q1 == 123
gen Q1_3 = 1 if Q1 == 3 | Q1 == 13 | Q1 == 23 | Q1 == 123

But this method is rather troublesome(the maximum
number of choices is seven, and there are as many as
more than 80 questions in the original data!) and easy
to mistype.
I'd like to know if there is some better way to do the
same thing.

Any suggestions welcome.

K.I.

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```