Cochran-Armitage Trend test interpretation

[dcortell]

Hi All

By applying the following code, I receive the following results.

I'm quite surprised by the significance of the Exact Rend test results, as the positive effect (opportunity-new) row percentage seems

pretty alternating overtime, and I would expect a no presence of any trend effect.

My question is, There could be something ongoing here which I'm missing that could make the test not reliable?

Bests

proc freq data=lead_att (where=(outcome_rev2 is not missing and outcome_rev2 not like '%Existing%') );
tables yy_event*outcome_rev2/cmh chisq nopercent nocol nopct trend ;
exact trend;
run;

[Ksharp]

I think you could trust result :  there is a trend due to p-value <0.05.

But the problem is you have a WARNING: count less than 5. if you could get rid of this warning that would be perfect.

[dcortell]

The warning should not be a problem here, as the Exact Cochran Test is intended to manage cases like these were obs<5 are present in cells.

[Ksharp]

OK. You are right. EXACT test take care of this situation.

[Ksharp]

I think you could trust result :  there is a trend due to p-value <0.05.

But the problem is you have a WARNING: count less than 5. if you could get rid of this warning that would be perfect.