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03-31-2011 03:14 PM

I have 2 cohorts with counts of an event for each. But I've calculated 3 different relative percentages - % of the overall cohort, % of all those patients who have evidence of the event and % of patients in a similar age group. So the denominator in the % changes for each.

I've done a chi-squared test but I don't think that's entirely what I want. Basically I want to test the 2-sample proportion values for each type of proportion to test whether p(cohort1)=p(cohort2) and I'm just not thinking clearly.

What am I missing??? Or doesn't it matter?

Sue

I've done a chi-squared test but I don't think that's entirely what I want. Basically I want to test the 2-sample proportion values for each type of proportion to test whether p(cohort1)=p(cohort2) and I'm just not thinking clearly.

What am I missing??? Or doesn't it matter?

Sue

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03-31-2011 07:53 PM

I think rather than %, calculate freq/counts and then you can use a proc freq to get the difference between cohorts for the different ratios and calculate odds ratio between the two.

Hopefully someone can verify that's correct...

Hopefully someone can verify that's correct...

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04-04-2011 12:13 AM

How about:

[pre]

proc freq data=data;

tables a*b /chisq riskdiff;

run;

[/pre]

riskdiff will give difference in proportion and its limited interval.

Ksharp

[pre]

proc freq data=data;

tables a*b /chisq riskdiff;

run;

[/pre]

riskdiff will give difference in proportion and its limited interval.

Ksharp