```Date: Tue, 12 May 1998 09:05:54 -0600 Reply-To: "A. PAUL BEAULNE" Sender: "SPSSX(r) Discussion" From: "A. PAUL BEAULNE" Subject: Re: ROC curves for yes/no response Comments: To: Jeff Mather In-Reply-To: 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 analysis 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 done. 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 will 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. > thanks > ```

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