BookmarkSubscribeRSS Feed
🔒 This topic is solved and locked. Need further help from the community? Please sign in and ask a new question.
proctice
Quartz | Level 8

The logit model part of a ZIP model models the extra zeros as the outcome, but my client wants the probability of a count greater than 0 instead.  Is it appropriate to do 2 completely separate models - a proc logistic modeling count>0 and a proc genmod with the zeros excluded modeling the count part?

 

1 ACCEPTED SOLUTION

Accepted Solutions
Rick_SAS
SAS Super FREQ

You can invert odds ratios by using the EVENT= option on the response variable on the MODEL statement.

Instead of 

model y(event="0") = x1 x2 x3;

you can invert the odds ratio by using

model y(event="1") = x1 x2 x3;

 

View solution in original post

3 REPLIES 3
Rick_SAS
SAS Super FREQ

I think I would stick with the ZIP model. You can use GENMOD or PROC FMM. The model will predict the probability of a zero count, which is P(Y=p | x). The client wants "one minus that predicted probability": 1 - P(Y=0| x)

proctice
Quartz | Level 8

They are more interested in the odds ratios being in the right direction, can I just invert them?

Rick_SAS
SAS Super FREQ

You can invert odds ratios by using the EVENT= option on the response variable on the MODEL statement.

Instead of 

model y(event="0") = x1 x2 x3;

you can invert the odds ratio by using

model y(event="1") = x1 x2 x3;

 

sas-innovate-2024.png

Available on demand!

Missed SAS Innovate Las Vegas? Watch all the action for free! View the keynotes, general sessions and 22 breakouts on demand.

 

Register now!

What is ANOVA?

ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.

Find more tutorials on the SAS Users YouTube channel.

Discussion stats
  • 3 replies
  • 1807 views
  • 1 like
  • 2 in conversation