Programming the statistical procedures from SAS

Data analysis in SAS - anova

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New Contributor
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Data analysis in SAS - anova

I tested 4 different sugar solutions in 20 healthy volunteers. They had to drink the solutions until they were satiated.

So my question is: Is there a significant difference in drinking time between the 4 solutions?

 

I want to analyze it with SAS, but I'm not sure which syntax to use. I've already run ANOVA, but the resulting p-value is not consistent with the p-value I found using GraphPad Prism. I think it's because SAS did a normal ANOVA, but it has to be a repeated measures ANOVA with multiple comparisons.

 

I tried a lot of different commands in SAS, but I'm not sure which one is the right one. So if anybody could help me? Would be nice Smiley Happy

 

Cheers!

Trusted Advisor
Posts: 1,679

Re: Data analysis in SAS - anova

You say you think it should be a repeated measures analysis, but there's nothing in your decription that indicates repeated measures was actually performed. You said: "I tested 4 different sugar solutions in 20 healthy volunteers. They had to drink the solutions until they were satiated."

 

So can you explain further?

New Contributor
Posts: 2

Re: Data analysis in SAS - anova

 

Yes, so, these 20 volunteers all tested the 4 different solutions at different study days. So that's why it is repeated (with the same subjects and the same solutions for every subject). 

 

Frequent Contributor
Posts: 140

Re: Data analysis in SAS - anova

You are right that you have dependent data because "time to satiety" will partly depend on the person.

 

RM ANOVA is one way to analyze such data, and it can be done in SAS, but RM ANOVA makes rather strong assumptions (it assumes sphericity) and a better way to analyze such data is with multilevel models.  Since your DV is continuous, then PROC MIXED is probably a good place to start.

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