Transposing repeated measures data - can't create time variable correctly

Question

I have data with ID, repeated cognitive measure (cog1-cog6), and medication (SSRI) at start. I will eventually run the mixed procedure to determine the association between cognitive score at the time points and SSRI.

My code looks like:

**getting relevant variables;

data ucognition;
set analyze (keep=
HHIDPN SSRI 
cog1 cog2 cog3 cog4 cog5 cog6); 
run;


proc transpose data=ucognition out=longcog (rename =(col1=CogScore) rename = (_name_=cog));
by HHIDPN SSRI;
var cog1 cog2 cog3 cog4 cog5 cog6;
run;

proc print data=longcog (obs=10);
run;

Through this point, everything works fine (i think?). The following code is where I am trying to create a time variable:

data longcog2;
set longcog;
cog=cog1; time=1; output;
cog=cog2; time=2; output;
cog=cog3; time=3; output;
cog=cog4; time=4; output;
cog=cog5; time=5; output;
cog=cog6; time=6; output;
keep HHIDPN SSRI time cog;
run;

proc print data=longcog2 (obs=10);
run;

Here, SAS says that cog1, cog2, cog3, cog4, cog5, cog6 have not been initialized.

Obs   hhidpn    SSRI    cog    time 
1 10210020 No SSRI 14 1 
2 10210020 No SSRI 13 2 
3 10210020 No SSRI 10 3 
4 10210020 No SSRI 14 4 
5 10210020 No SSRI 10 5 
6 10210020 No SSRI 11 6 

I am not sure how to fix this, and have tried running various procedures with them, but nothing happens when I try to specifically do the time creation. All of my variables are numeric, so i dont think that is the issue.

I have also tried running like this:

data ucognition;
set analyze (keep=
HHIDPN SSRI 
cog1 cog2 cog3 cog4 cog5 cog6); 
run;


proc transpose data=ucognition out=longcog (rename =(col1=CogScore) rename = (_name_=cog));
by HHIDPN SSRI **cog1 cog2 cog3 cog4 cog5 cog6**;
var cog1 cog2 cog3 cog4 cog5 cog6
    ;
run;

proc print data=longcog (obs=10);
run;

data longcog2;
set longcog;
cog=cog1; time=1; output;
cog=cog2; time=2; output;
cog=cog3; time=3; output;
cog=cog4; time=4; output;
cog=cog5; time=5; output;
cog=cog6; time=6; output;
keep HHIDPN SSRI time cog;
run;

proc print data=longcog2 (obs=10);
run;

This works, but it repeats for each person 6 times shown here:

Obs hhidpn SSRI cog time 
1 10210020 No SSRI 14 1 
2 10210020 No SSRI 13 2 
3 10210020 No SSRI 10 3 
4 10210020 No SSRI 14 4 
5 10210020 No SSRI 10 5 
6 10210020 No SSRI 11 6 
7 10210020 No SSRI 14 1 
8 10210020 No SSRI 13 2 
9 10210020 No SSRI 10 3 
10 10210020 No SSRI 14 4 
11 10210020 No SSRI 10 5 
12 10210020 No SSRI 11 6 

Is there a reason "cog" which is my rename name=cog variable, wont store cog1-cog6? They are named r7cogtot-r12cogtot in the initial data, but I was told to rename them this way

I transposed to long data as normal. I tried to create a time variable based on the repeated cognition score, but SAS wont let me use 'cog' to hold cog1-cog6 and I am not sure how to fix

Answer 1

The transpose is of ucognition which apparently has the variables cog1 through cog6.

Try

data longcog2;
set ucognition ;
...

instead of

data longcog2;
set longcog;
...

Answer 2

Those variables are not on the dataset you are reading because you transposed them into observations instead. Use the original dataset if you want the original structure.

Why not just use the transposed dataset as it is? You might just be able to use the character variable for your time category (you named if COG).

If you need to convert it to a numeric just use substr() to pull the numeric suffix off of the name and INPUT() to convert the string to a number.

data longcog2;
  set longcog;
  time = input(substr(cog,4),32.);
  rename CogScore=cog;
  keep HHIDPN SSRI time CogScore;
run;