Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-16 Thread Frank E Harrell Jr
Gad Abraham wrote: Frank E Harrell Jr wrote: Gad Abraham wrote: This approach leaves much to be desired. I hope that its practitioners start gauging it by the mean squared error of predicted probabilities. Is the logic here is that low MSE of predicted probabilities equals a better calibra

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-15 Thread Gad Abraham
Frank E Harrell Jr wrote: Gad Abraham wrote: This approach leaves much to be desired. I hope that its practitioners start gauging it by the mean squared error of predicted probabilities. Is the logic here is that low MSE of predicted probabilities equals a better calibrated model? What abou

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-15 Thread Frank E Harrell Jr
Gad Abraham wrote: This approach leaves much to be desired. I hope that its practitioners start gauging it by the mean squared error of predicted probabilities. Is the logic here is that low MSE of predicted probabilities equals a better calibrated model? What about discrimination? Perfect c

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-15 Thread Gad Abraham
This approach leaves much to be desired. I hope that its practitioners start gauging it by the mean squared error of predicted probabilities. Is the logic here is that low MSE of predicted probabilities equals a better calibrated model? What about discrimination? Perfect calibration implies p

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-14 Thread Frank E Harrell Jr
Gabor Grothendieck wrote: On Mon, Oct 13, 2008 at 11:47 PM, Frank E Harrell Jr <[EMAIL PROTECTED]> wrote: Gabor Grothendieck wrote: On Mon, Oct 13, 2008 at 11:21 PM, Frank E Harrell Jr <[EMAIL PROTECTED]> wrote: [EMAIL PROTECTED] wrote: I recall a concept of Snout: sensitivity that is high e

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Gabor Grothendieck
On Mon, Oct 13, 2008 at 11:47 PM, Frank E Harrell Jr <[EMAIL PROTECTED]> wrote: > Gabor Grothendieck wrote: >> >> On Mon, Oct 13, 2008 at 11:21 PM, Frank E Harrell Jr >> <[EMAIL PROTECTED]> wrote: >>> >>> [EMAIL PROTECTED] wrote: I recall a concept of Snout: sensitivity that is high enou

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
Gabor Grothendieck wrote: On Mon, Oct 13, 2008 at 11:21 PM, Frank E Harrell Jr <[EMAIL PROTECTED]> wrote: [EMAIL PROTECTED] 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 essent

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
/2008 4:41 PM >>> - Original Message - From: "Frank E Harrell Jr" <[EMAIL PROTECTED]> To: "John Sorkin" <[EMAIL PROTECTED]> Cc: ; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Monday, October 13, 2008 2:09 PM Subject: Re: [R] Fw: Lo

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Gabor Grothendieck
On Mon, Oct 13, 2008 at 11:21 PM, Frank E Harrell Jr <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] 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 th

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
r, Ph.D." <[EMAIL PROTECTED]> 10/13/2008 4:41 PM >>> - Original Message - From: "Frank E Harrell Jr" <[EMAIL PROTECTED]> To: "John Sorkin" <[EMAIL PROTECTED]> Cc: ; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Monday, O

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
/diagnostictests.html --Chris Ryan Original message Date: Mon, 13 Oct 2008 18:14:39 -0400 From: "John Sorkin" <[EMAIL PROTECTED]> Subject: Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC) To: "Ph.D. Robert W. Baer" <[EMAIL PROTECTED]>, "Frank

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
Robert W. Baer, Ph.D. wrote: - Original Message - From: "Frank E Harrell Jr" <[EMAIL PROTECTED]> To: "John Sorkin" <[EMAIL PROTECTED]> Cc: ; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Monday, October 13, 2008 2:09 PM Subject: Re: [R]

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Greg Snow
AIL PROTECTED] Sent: Monday, October 13, 2008 4:14 PM To: Ph.D. Robert W. Baer; Frank E Harrell Jr Cc: r-help@r-project.org; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC) Of course Prof Baer is correct the positive predictive value (PP

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread cryan
the higher the specificity, the greater the PPV? http://www.musc.edu/dc/icrebm/diagnostictests.html --Chris Ryan Original message >Date: Mon, 13 Oct 2008 18:14:39 -0400 >From: "John Sorkin" <[EMAIL PROTECTED]> >Subject: Re: [R] Fw: Logistic regresion - Interp

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread John Sorkin
Indeed, however as I stated in my prior Email, the cases of a 0 or 1 prevalence are degenerative and are of little practical importance. And as noted in my EMail message, I was talking about values of PPV and NPV as a function of sensitivity and specificity when the prevalence is fixed. John John

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Peter Dalgaard
John Sorkin wrote: Of course Prof Baer is correct the positive predictive value (PPV) and the negative predictive values (NPV) serve the function of providing conditional post-test probabilities PPV: Post-test probability of disease given a positive test NPV: Post-test probability of no disease g

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread John Sorkin
gt;> - Original Message - From: "Frank E Harrell Jr" <[EMAIL PROTECTED]> To: "John Sorkin" <[EMAIL PROTECTED]> Cc: ; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Monday, October 13, 2008 2:09 PM Subject: Re: [R] Fw: Logistic regresion - Int

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Robert W. Baer, Ph.D.
- Original Message - From: "Frank E Harrell Jr" <[EMAIL PROTECTED]> To: "John Sorkin" <[EMAIL PROTECTED]> Cc: ; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Monday, October 13, 2008 2:09 PM Subject: Re: [R] Fw: Logistic regresion - I

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
John Sorkin wrote: Frank, Perhaps I was not clear in my previous Email message. Sensitivity and specificity do tell us about the quality of a test in that given two tests the one with higher sensitivity will be better at identifying subjects who have a disease in a pool who have a disease, and th

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread John Sorkin
Frank, Perhaps I was not clear in my previous Email message. Sensitivity and specificity do tell us about the quality of a test in that given two tests the one with higher sensitivity will be better at identifying subjects who have a disease in a pool who have a disease, and the more sensitive t

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
John Sorkin wrote: Jumping into a thread can be like jumping into a den of lions but here goes . . . Sensitivity and specificity are not designed to determine the quality of a fit (i.e. if your model is good), but rather are characteristics of a test. A test that has high sensitivity will proper

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread John Sorkin
Jumping into a thread can be like jumping into a den of lions but here goes . . . Sensitivity and specificity are not designed to determine the quality of a fit (i.e. if your model is good), but rather are characteristics of a test. A test that has high sensitivity will properly identify a large

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Frank E Harrell Jr
Maithili Shiva wrote: Dear Mr Peter Dalgaard and Mr Dieter Menne, I sincerely thank you for helping me out with my problem. The thing is taht I already have calculated SENS = Gg / (Gg + Bg) = 89.97% and SPEC = Bb / (Bb + Gb) = 74.38%. Now I have values of SENS and SPEC, which are absolute in n

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Dieter Menne
sungard.com> writes: > There are two good papers that illustrate how to compare classifiers > using Sensitivity and Specificity and their extensions (e.g., likelihood > ratios, young index, KL distance, etc). > > See: > 1) Biggerstaff, Brad, 2000, "Comparing diagnostic tests: a simple > graphi

Re: [R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Pedro.Rodriguez
forementioned papers. Kind Regards, Pedro -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Maithili Shiva Sent: Monday, October 13, 2008 3:28 AM To: r-help@r-project.org Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: [R] Fw: Logistic regresion - Int

[R] Fw: Logistic regresion - Interpreting (SENS) and (SPEC)

2008-10-13 Thread Maithili Shiva
Dear Mr Peter Dalgaard and Mr Dieter Menne, I sincerely thank you for helping me out with my problem. The thing is taht I already have calculated SENS = Gg / (Gg + Bg) = 89.97% and SPEC = Bb / (Bb + Gb) = 74.38%. Now I have values of SENS and SPEC, which are absolute in nature. My question was