topic Re: Creating a binary variable from consecutive values from different variables in SAS Programming

Creating a binary variable from consecutive values from different variables

amrodri — Thu, 02 Oct 2014 17:54:11 GMT

Hello I am not sure if someone could help me with the following:

I have a longitudinal dataset of a binary variable that is equal to 1 when there is an infection in a patient, otherwise it is 0. Sometimes infections persist for seveal visits, sometimes they only remain for one visit and the patient is cured.I want to create 3 variables (X!, X2, X3) that would indicate a 1 or a 0 according to the following criteria:

In other words, this is how is might look and what I which to have my program do:

ID visit1 visit2 visit3 visit4 VARIABLE X1 VARIABLE X2 VARIABLE X3

1 0 0 0 0 0 0 0

2 0 1 0 0 0 1 0

3 1 1 0 0 1 1 0

4 0 1 1 1 1 1 1

5 0 1 0 1 0 1 0

X1) Variable is = 1 when there is an infection for At least two or more consecutive visits per patient.

X2) Variable is = 1 when there is an infection for At least one visits per patient (Any infection).

X3) Variable is = 1 when there is an infection for At least three or more consecutive visits per patient.

Anyone can help me? I do not know how to solve this.

Thank youse

Re: Creating a binary variable from consecutive values from different variables

data_null__ — Thu, 02 Oct 2014 18:27:42 GMT

Something like this perhaps.

data visit;
   input id v1-v4;
   length r $4; 
   r=cats(of v:);
   x1=not not find(r,'11');
   x2=not not find(r,'1');
   x3=not not find(r,'111');
   cards; 
1 0 0 0 0 
2 0 1 0 0 
3 1 1 0 0 
4 0 1 1 1 
5 0 1 0 1 
;;;;
   run; 
proc print; 
   run;

Re: Creating a binary variable from consecutive values from different variables

RamKumar — Fri, 03 Oct 2014 15:12:39 GMT

How does 'not not find' works here? Is it a function by any chance?

Re: Creating a binary variable from consecutive values from different variables

data_null__ — Fri, 03 Oct 2014 16:24:48 GMT

NOT is a Boolean operator, in this case NOT NOT turns the position returned by FIND into 1 or ZERO making a Boolean of it.

Re: Creating a binary variable from consecutive values from different variables

Haikuo — Fri, 03 Oct 2014 16:33:19 GMT

Or to use parenthesis to get the Boolean: x1=(find(r,'11')>0);