On Aug 20, 2010, at 8:25 AM, Iasonas Lamprianou wrote:

Thanks, I'll try to put my hands on the reference
By the way, would it be easier if I just checked out the code by which the glm function computes the residuals? Or maybe this is not a very good idea. And if it is, how can I check out the source, I never really found out!


the glm functions calls glm.fit and in the middle of the glm.fit function is this call to a Fortran routine:

fit <- .Fortran("dqrls", qr = x[good, ] * w, n = ngoodobs,
                p = nvars, y = w * z, ny = 1L, tol = min(1e-07,
                  control$epsilon/1000), coefficients = double(nvars),
residuals = double(ngoodobs), effects = double(ngoodobs), rank = integer(1L), pivot = 1L:nvars, qraux = double(nvars),
                work = double(2 * nvars), PACKAGE = "base")

So unless you read Fortran, you may be out of luck, and generally those who do read Fortran already know how to get at source code without asking on mailing list. But if you want to pursue an effort at viewing the source, try reading Ligges' article, "Accessing the sources", in:

http://cran.r-project.org/doc/Rnews/Rnews_2006-4.pdf

--
David

jason

Dr. Iasonas Lamprianou


Assistant Professor (Educational Research and Evaluation)
Department of Education Sciences
European University-Cyprus
P.O. Box 22006
1516 Nicosia
Cyprus
Tel.: +357-22-713178
Fax: +357-22-590539


Honorary Research Fellow
Department of Education
The University of Manchester
Oxford Road, Manchester M13 9PL, UK
Tel. 0044  161 275 3485
iasonas.lampria...@manchester.ac.uk


--- On Fri, 20/8/10, David Winsemius <dwinsem...@comcast.net> wrote:

From: David Winsemius <dwinsem...@comcast.net>
Subject: Re: [R] Deviance Residuals
To: "Iasonas Lamprianou" <lampria...@yahoo.com>
Cc: r-help@r-project.org
Date: Friday, 20 August, 2010, 13:20

On Aug 20, 2010, at 5:54 AM, Iasonas Lamprianou wrote:

Dear all,

I am running a logistic regression and this is the
output:

glm(formula = educationUniv ~ brncntr, family =
binomial)

Deviance Residuals:
    Min
   1Q   Median
   3Q      Max  #
αυτά είναι τα υπόλοιπα
-0.8825  -0.7684
-0.7684   1.5044   1.6516

Coefficients:
            Estimate Std.
Error z value Pr(>|z|)
(Intercept) -1.06869    0.01155
-92.487   <2e-16 ***
brncntrNo    0.32654
0.03742   8.726   <2e-16
***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05
'.' 0.1 ' ' 1

(Dispersion parameter for binomial family taken to be
1)

Null deviance: 49363  on 42969  degrees of
freedom
Residual deviance: 49289  on 42968  degrees
of freedom
AIC: 49293


I thought that the residuals should all be restricted
in the range 0 to 1 (since I am predicting a binary
outcome).

The internal regression calculations are done on the
log-odds scale so the working residuals are on that scale.
Those are stored in the glm.obj as the "residuals" item. I
believe that if you tried mean(glm.obj$residuals) you should
get 0.  Presumably the deviance residuals are offered
in preference to the working residuals because the deviance
residual's use as an influence measure is made readily
interpretable by reference to chi-square statistics. Page
205 of the Hastie and Pregibon citation has all the
definitions.

--David.



I read many posts on this list and I realized that
there are four(!?) different types of residuals. I need a
simple account of these four types of residuals, if anyone
can help it will be great.

residuals(glm1, "response")
residuals(glm1, "pearson")
residuals(glm1, "deviance")
residuals(glm1, "working") - especially this one
confuses me a lot!

What is the "working" option and how is this
different?

Thank you
Jason

Dr. Iasonas Lamprianou

--
David Winsemius, MD
West Hartford, CT






David Winsemius, MD
West Hartford, CT

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