st: Comparing AUC for weighted samples in Stata?

[Stian Lydersen <stian.lydersen@ntnu.no>]

We have weighted samples from 4 strata of pre-school children. The 
strata sizes vary from 1095 to 194, and the sampling probabilities vary 
from 0.37 to 0.89, with highest sampling probabilities is the strata 
with high risk of diagnosis of a mental health problem. (The diagnosis, 
a gold standard, is established through an interview).

We investigate if the sum score from one or more questionnaires can be 
used as diagnostic screening instrument.

We have been able to compute ROC, and an estimate and CI for AUC using 
the suggestion on
http://www.stata.com/statalist/archive/2009-01/msg00689.html

In addition we want to do the following:
Compare the AUC for sum scores from two separate screeing instruments 
(on the same samples). Estimate, CI and p-value for difference?

Added value: Assume we use of screening instrument 2 in addition to 
screening instrument 1, for example estiamte a logistic regression model 
with predictro 1 alone, and the predictor 1 and 2. How much added value 
(in terms of AUC estimate CI and p-value) does this give?

Do you know where we can find info on how to do this, preferably in Stata?


Regards, Stian Lydersen and Trude Hamre Sveen

e-mail stian.lydersen@ntnu.no


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