Help using Base SAS procedures

calculating wald confidence intervals? please help

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Occasional Contributor
Posts: 18

calculating wald confidence intervals? please help

http://i60.tinypic.com/2coppiw.png

Hiya, not sure how to calculate a confidence interval, particularly the standard error

My teacher said it's "exp(B1 + B4 +/- 1.96* sqrt(se(B1) + se(B4) + 2cov(B1,B4) )"

where B1 is the factor and B4 is the interaction term (estimates).

xxx

Occasional Contributor
Posts: 18

Re: calculating wald confidence intervals? please help

obviously i think she's wrong! otherwise i wouldn't be on here... xx

Super User
Posts: 17,828

Re: calculating wald confidence intervals? please help

You haven't provided enough info. What proc are you using, what code, options?

If its survival analysis and you need WALD CI for hazard ratio you can use the CL=WARD option on the hazard ratio statement.

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