Programming the statistical procedures from SAS

Question for within and between subject

Reply
Occasional Contributor
Posts: 5

Question for within and between subject

The data order is ID, Group(0=placebo and 1= treatment), Time (0-3), Grip Strength, Status (0= no pain and 1 = pain)


I need to write the within-subjects and between-subjects models considering only a random subject effect and random intercept model.

Should I just use this the code like following one?


*random intercept;

PROC MIXED data=HW5.imp1 METHOD=ML COVTEST;

CLASS id;

MODEL implant = time /SOLUTION residual;

RANDOM INTERCEPT /SUB=id TYPE=UN G;

run;

ThanksQuestion for within and between subject

Attachment
Respected Advisor
Posts: 2,655

Re: Question for within and between subject

I would also account for within subject correlation, with a repeated statement.  My preferred code would be:

proc glimmix data=hw5.imp1;

class id time;

model implant = time/solution;

random time/residual subject=id type=un;

run;

This provides the most direct between-within subject approach. Under the unstructured covariance approach, a random subject effect is completely confounded with the residual parameterization. For other structures, such as autoregressive structures for equally spaced in time measurements, the random effect of subject can be captured as:

proc glimmix data=hw5.imp1;

class id time;

model implant = time/solution;

random intercept/subject=id;

random time/residual subject=id type=un;

run;

Steve Denham

Ask a Question
Discussion stats
  • 1 reply
  • 336 views
  • 3 likes
  • 2 in conversation