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# re: st: Area under the curve and C-statistics

 From "Ariel Linden, DrPH" To Subject re: st: Area under the curve and C-statistics Date Fri, 26 Oct 2012 11:12:30 -0400

```Hi Amal,

-lroc- is a post-estimation command for running after logistic regression,
so it is not surprising that you got that error.

It seems to me that since a multinomial regression is basically a series of
logistic models, you could run each model separately (i.e., 2 vs 1, 3 vs 1,
4 vs 1, etc.) and then plot all those results together using -roccomp-.

Perhaps there is another way of doing this, but I just did a google search
and didn't find any relevant results.

Ariel

Date: Thu, 25 Oct 2012 19:38:49 +0000
From: Amal Khanolkar <Amal.Khanolkar@ki.se>
Subject: st: Area under the curve and C-statistics

Hi,

I've used C statistics before and produced graphs that depict area under the
curve for logistic regression models.

Is it possible to do the same for multinomial logistics regression models?

I tried running:

mlogit moth_wtgainbybmi i.mom_race2 age_mom sexx, base(1) rrr, if parity!=.
& gestwk_cat!=. & cigs_befx!=. & cigs_1stx!=. & cigs_2ndx!=. & cigs_3rdx!=.
& gestdb!=. & gesthy!=. & ht_cm!=. & plural==1 & edu_mom!=. & marriedxx!=.

lroc

I assume that 'lroc' is suitable after using the 'logistic' command.

Is there an equivalent for 'lroc' and 'roccomp' for multinomial logistic
regression?

Thanks,

/Amal.

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