[R] Question on WLS (gls vs lm)

2010-06-24 Thread Stats Wolf
explain why? Are these different types of weights? Many thanks in advance, Stats Wolf __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide

Re: [R] Question on WLS (gls vs lm)

2010-06-24 Thread Stats Wolf
is just a special case? Best, Stats Wolf On Thu, Jun 24, 2010 at 12:49 PM, Joris Meys jorism...@gmail.com wrote: Isn't that exactly what you would expect when using a _generalized_ least squares compared to a normal least squares? GLS is not the same as WLS. http://www.aiaccess.net/English

Re: [R] Question on WLS (gls vs lm)

2010-06-24 Thread Stats Wolf
Indeed, they should give the same results, and hence I was worried to see that the results were not that same. Suffice it to look at standard errors and p-values: they do differ, and the differences are not really that small. Thanks, Stats Wolf On Thu, Jun 24, 2010 at 2:39 PM, Joris Meys

[R] polr for ordered multinomial response without additional variables

2010-02-02 Thread Stats Wolf
think, modeled with polr: fit-polr(result~1) summary(fit) Could you please explain me what do the coefficients from the above summary mean? And how I could use the t-test (eg, what are degrees of freedom, for example? What is the exact hypothesis being tested here?)? Thank you, Stats Wolf

[R] A model-building strategy in mixed-effects modelling

2010-01-18 Thread Stats Wolf
for a situation that calls for mixed effects? Of course, the example above is overly simplistic, yet such situations can occur -- from a complex model with a couple of random terms one can finally get to a simple fixed-effects model. Please comment. Thanks in advance, Stats Wolf

[R] Reporting discriminat analysis

2009-10-23 Thread Stats Wolf
. However, I cannot find these cut-off values. I use the function lda of the MASS package, although I have also looked at some other procedures for discriminant analysis, and equally failed. Thanks, Stats Wolf __ R-help@r-project.org mailing list https

[R] Multinomial logistic regression in an ANOVA-like framework

2009-06-12 Thread Stats Wolf
look at means when interpreting the results) I would like to make some kind of multiple comparisons, if it is at all possible. Any suggestions if I am doing anything wrong and if not, what could I do to get these multiple comparisons? Thank you, Stats Wolf

[R] glht problem

2009-05-19 Thread Stats Wolf
I am struggling with a simple repeated-measure model: fit-lme(trait~year * A, random = ~1|subj/year) A being a factor with three levels. I got have the following results for anova(fit): numDF denDF F-value p-value (Intercept) 1 126 2471.4720 .0001 year 2060

Re: [R] Graphical output format

2009-05-14 Thread Stats Wolf
it eliminates that huge margin on top of the output pj On Wed, May 13, 2009 at 11:47 PM, Stats Wolf stats.w...@gmail.com wrote: Dear colleagues, Saving a plot with pdf gives a very nice result: pdf(myplot.pdf) par(font=1,family='serif') plot(pressure) dev.off() Doing the very same with other

[R] Graphical output format

2009-05-13 Thread Stats Wolf
Dear colleagues, Saving a plot with pdf gives a very nice result: pdf(myplot.pdf) par(font=1,family='serif') plot(pressure) dev.off() Doing the very same with other formats (png, jpeg, tiff) gives far worse results. Is there anything to do to make a plot in some other format than pdf look like

[R] Longitudinal study with three treatments

2009-03-24 Thread Stats Wolf
Hi, I am comparing three treatments. The data come from a longitudinal study, and for each treatment I have only 1 case, on which the observations across 20 years are made. My main aim is to compare the three treatments, but the effect of time is of interest as well. Which of the many R functions