Help using Base SAS procedures

Assymetrical confidence intervals in PHREG, how possible?

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Assymetrical confidence intervals in PHREG, how possible?

Hi all,

 

 

This afternoon I decided to plot my hazard ratio's and confidence intervals in a forest plot (horizontal bars). However, when I plot my effect sizes and confidence intervals, they are not symmmetrical (e.g. the length from the effect size to the upper and lower bound are not equal....). I have no clue how this could have happened.

 

I obtained by data with the PHREG procedure. The piece of syntax I used looks basically like this:

 

PROC PHREG data=mydata;

CLASS var1 var2 var3/ref=first;

MODEL survival*censor(0) = var1 var2 var3 / RL;

RUN;

 

Really hope someone can help me out!

 

Kind regards,

Marjolein

 

 

 


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‎01-02-2017 03:16 PM
Super User
Posts: 19,820

Re: Assymetrical confidence intervals in PHREG, how possible?

Posted in reply to Marjolein

I believe this is correct. Your likely plotting on a linear scale, while the model developed is an exponential model. 

Answe is similar to this :

 

 

http://stats.stackexchange.com/questions/4713/binomial-confidence-interval-estimation-why-is-it-not-...

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Solution
‎01-02-2017 03:16 PM
Super User
Posts: 19,820

Re: Assymetrical confidence intervals in PHREG, how possible?

Posted in reply to Marjolein

I believe this is correct. Your likely plotting on a linear scale, while the model developed is an exponential model. 

Answe is similar to this :

 

 

http://stats.stackexchange.com/questions/4713/binomial-confidence-interval-estimation-why-is-it-not-...

Contributor
Posts: 23

Re: Assymetrical confidence intervals in PHREG, how possible?

Ah! That makes sense!!! Thank you so much. This is quite a relief Smiley Happy

SAS Super FREQ
Posts: 3,753

Re: Assymetrical confidence intervals in PHREG, how possible?

Posted in reply to Marjolein

By default the oddsratio plot is on a linear scale. You can use the LOGBASE=10 option on the PLOTS=ODDSRATIO option to generate the oddsratio plot on a log scale, which I think is more natural. See the discussion and example in the article "Odds ratio plots with a logarithmic scale in SAS."

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