Date: Tue, 12 May 1998 09:05:54 -0600
Reply-To: "A. PAUL BEAULNE" <A.BEAULNE@V-WAVE.COM>
Sender: "SPSSX(r) Discussion" <SPSSX-L@UGA.CC.UGA.EDU>
From: "A. PAUL BEAULNE" <A.BEAULNE@V-WAVE.COM>
Subject: Re: ROC curves for yes/no response
Content-Type: text/plain; charset="iso-8859-1"
I am going to take a stab at this but I am not an expert in this form of
My understanding of ROC's is that one uses
different cut off points along a scale to make decisions
For example the SAT scores that are employed for admission to university
or a scale to decided if a particular treatment or diagnostic should be
With each cut of score there is an associated sensitivity (true positive)
and specificity (true negative).
By employing several cut off scores at which a decision is made one then
have a number of pairs of S&S measures.
Plot these pairs will give the ROC curves
Decisions with respect to the "Best" cut score can be made through analysis
of the ROC curve
Therefore I have no way of understanding how your question can be answered
given what I have just said
> -----Original Message-----
> From: SPSSX(r) Discussion [mailto:SPSSX-L@UGA.CC.UGA.EDU]On Behalf Of
> Jeff Mather
> Sent: May 12, 1998 8:01 AM
> To: SPSSX-L@UGA.CC.UGA.EDU
> Subject: ROC curves for yes/no response
> This is a bit off the SPSS path, but can anyone tell me if there
> is any way
> to use a nominal response to draw an ROC curve? I'd like to compare
> ultra-brief (one question) instruments for a diagnosis of depression (yes
> or no) with standard questionnaire that uses a cutoff on an
> interval scale.
> My assumption was that this could not be done with a y/n response; that
> you need at least a three point ordinal scale (ie. always, sometimes,
> never) to be able to draw the curve.