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Posted 10-25-2018 12:21 PM
(2344 views)

What methods are available if there are no responses in a 2x2 table. For example, when analyzing proportion differences between treatments by Gender, neither Male nor Female have any responses (e.g. the counts are zero for both), so FREQ will not estimate the CIs for the difference in proportion. To get around this, I placed a very small non-zero value in the counts table, say 0.000000001 for the zero response counts and then processed it with FREQ using EXACT and RISKDIFF. Should some other method be used, and if so, what is it?

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Alright so are the CLs obtained through an ODS table or through an output statement? I tried an output statement but the columns are not easily discerned.

In addition, the small weights do not appear to work as the CI for the risk difference column where the zero weights occur are still showing missing values. Below shows the code I used after applying the small weights.

proc freq data = countsfreq;

by subgroupan subgroupa group ;

table trtp*ev /out = x riskdiff (cl=newcombe) nowarn alpha = 0.1;

weight count/zeros;

/* exact riskdiff;*/

/* ods output riskdiffcol2 = ci1 ;*/

output out = rd2 riskdiff2;

run;

If I use the riskdiff statement my version of SAS only allows (method = score) and with the options above it produces no CI values for the items with zero responses.

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