[R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)
Frank E Harrell Jr
f.harrell at vanderbilt.edu
Tue Oct 14 05:21:10 CEST 2008
cryan at binghamton.edu wrote:
> I recall a concept of Snout: sensitivity that is high enough to essentially rule out the presence of disease. And Spin: specificity that is high enough to essentially rule in the presence of disease.
> So perhaps the below is backwards? The higher the sensitivity, the greater the NPV? And the higher the specificity, the
greater the PPV?
Why should we care when we can directly estimate Prob(disease | test
results and risk factors)? Am I the only person who likes logistic
regression models this week?
> --Chris Ryan
> ---- Original message ----
>> Date: Mon, 13 Oct 2008 18:14:39 -0400
>> From: "John Sorkin" <jsorkin at grecc.umaryland.edu>
>> Subject: Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)
>> To: "Ph.D. Robert W. Baer" <rbaer at atsu.edu>, "Frank E Harrell Jr" <f.harrell at vanderbilt.edu>
>> Cc: r-help at r-project.org, dieter.menne at menne-biomed.de, p.dalgaard at biostat.ku.dk
> . . . . .
>> Further, PPV is a function of sensitivity (for a given specificity in a population with a given disease prevalence), the higher the sensitivity almost always the greater the PPV (it can by unchanged, but I don't believe it can be lower) and as
>> NPV is a function of specificity (for a given sensitivity in a population with a given disease prevelance), the higher the specificity almost always the greater the NPV (it can by unchanged, but I don't believe it can be lower) . . . .
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Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
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