topic Re: new variable with if then statements in SAS Procedures

new variable with if then statements

starz4ever2007 — Tue, 09 Aug 2016 21:08:50 GMT

dataset:

subj q1 q2 q3 q4 q5 q_total newvar

1 1 3.1 2.1 1 1 8.2

2 1 2.1 4.1 1 3 11.2

3 1 1.2 1 0 1.1 4.3

4 0 1 0 1 0 2

i would like to creat a new variable (newvar), where if q1 <=1 and if q2 is <= 1 and if q3 is <=1 and if qtotal is <= 8, then newvar =1 , otherwise newvar =0.

so newvar would look like:

newvar

Re: new variable with if then statements

PGStats — Tue, 09 Aug 2016 21:17:30 GMT

newvar = q1 <=1 and q2 <= 1 and q3 <=1 and qtotal <= 8;

Re: new variable with if then statements

starz4ever2007 — Tue, 09 Aug 2016 21:28:00 GMT

hmm im not getting newvar to equal 1 with that code

Re: new variable with if then statements

ballardw — Tue, 09 Aug 2016 21:30:04 GMT

@PGStats is being very terse.

His solution works for what you are doing because SAS treats true results as 1 and false as 0. So Newvar is the result of all of those comparisons, true or false.

You may want to consider if "otherwise newvar=0" includes cases of missing values. Missing are less than any value. So in this specific interest if all of the q variables are missing then newvar would be 1.

Re: new variable with if then statements

starz4ever2007 — Tue, 09 Aug 2016 23:19:16 GMT

is adding q1 ne . and q2 ne . and q3 ne . to PG's statement the best option?

Re: new variable with if then statements

PGStats — Wed, 10 Aug 2016 01:53:19 GMT

Your logical expression yields true (=1) when q1, q2, q3, or q_total are missing because missing is considered by SAS as inferior to any non-missing value. You can change the expression so that missing values will yield false, as demonstrated:

data test;
input subj  q1   q2   q3   q4   q5    q_total;
newvarTrue = q1 <=1 and q2 <= 1 and q3 <=1 and q_total <= 8;
newvarFalse = -q1 >= -11 and -q2 >= -1 and -q3 >= -1 and -q_total >= -8;
datalines;
1       1    3.1  2.1   1    1        8.2
2       1    2.1  4.1   1    3      11.2       
3       1    1.2  1      0    1.1     4.3
4       0      1    0      1    0       2
5       .      1    0      1    0       2
;

proc print; run;

Add a comment in your code to explain the trick.

Re: new variable with if then statements

starz4ever2007 — Wed, 10 Aug 2016 02:07:24 GMT

thank you very much!