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Hi everyone. I am new-ish to using SAS and am hoping for some help on if my code is correct for what I am after. I have the following variables:
Medications: the total number of medications taken per person
Sex
1=male
2=female
AgeGroups
1=20-25
2=26-29
3=30-34
Interaction between Sex and AgeGroups:
AgeGroups*Sex
Income
1=Less than 20k
2=20,000 – 49,999
3=50,000 – 79,999
4=80,000 – 99,999
5=100,000 or more
I want to find out if any of the categorical demographic variables have a significant effect on the number of medications. Then I want to find out where the significant differences are between groups. I am using linear regression. After some Google searching, I have come up with the following code. Is it correct to get what I am looking for? Thanks.
proc glm data=mydata;
class Sex AgeGroups Income;
model Medications=Sex AgeGroups Income AgeGroups*Sex /solution;
lsmeans Sex AgeGroups Income AgeGroups*Sex /adjust=scheffe;
run; quit;
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What about the other interactions?
model Medications=Sex|AgeGroups|Income;
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@someone456 wrote:
Hi everyone. I am new-ish to using SAS and am hoping for some help on if my code is correct for what I am after. I have the following variables:
Medications: the total number of medications taken per person
Sex
1=male2=female
AgeGroups
1=20-25
2=26-29
3=30-34
Interaction between Sex and AgeGroups:
AgeGroups*Sex
Income
1=Less than 20k
2=20,000 – 49,999
3=50,000 – 79,999
4=80,000 – 99,999
5=100,000 or more
I want to find out if any of the categorical demographic variables have a significant effect on the number of medications. Then I want to find out where the significant differences are between groups. I am using linear regression. After some Google searching, I have come up with the following code. Is it correct to get what I am looking for? Thanks.
proc glm data=mydata;
class Sex AgeGroups Income;
model Medications=Sex AgeGroups Income AgeGroups*Sex /solution;
lsmeans Sex AgeGroups Income AgeGroups*Sex /adjust=scheffe;
run; quit;
Your question about differences between groups is answered by the LSMEANS statement. So I think this is the correct code.
Paige Miller
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I agree with @PaigeMiller that you are on the right track.
I agree with @PGStats that you need to consider whether to exclude other potential interactions among the fixed effects (and be able to justify their exclusion).
In addition, I would think of this as an ANOVA rather than a regression. Of course ANOVA is really just a special case of regression, but there are things we can apply in ANOVA models that we don't apply in regression (like LSMEANS as @PaigeMiller suggested). ANOVA models have assumptions (notably, normality and homogeneity of variance and independence) that you would need to assess for your analysis. SAS® for Linear Models, Fourth Edition is an excellent resource; these are topics that are also covered extensively in courses, and so there are resources available on the internet, in books, etc.
I hope this helps.