[R] question about chi values GLM
Dear all, I am making an analysis using a GLM using three explanatory variables and a response variable. I need to obtain a table similar to this one, http://postimg.org/image/5sau79wlt/r nevertheless, I have not been able to do it. I am having a hard time specially getting the chi square values. I would like to know how to obatin them. I have used the function ANOVA, but it shows me the deviance but not the Chi-Square values, can be used these values? I also would like to know what function could help me to make ad hoc comparisons for single variables and interactions. If any of you knows how to do both estimations, I would really appreciate it. All the best!!! This is my script a=read.table(ricis3.txt,header=T) attach(a) model7=glm(Count~Sex+Time+Behaviour+Sex*Time+Sex*Behaviour+Time+Behaviour*Sex,family=poisson) summary(model7) anova(model7,test=Chi) Sex TimeBehaviour Count MaleNight Exploring 189 MaleNight Interacting 11 MaleNight Feeding 170 MaleNight Mating 13 MaleNight Resting 240 MaleDay Exploring 58 MaleDay Interacting 1 MaleDay Feeding 12 MaleDay Mating 3 MaleDay Resting 399 Female Night Exploring 187 Female Night Interacting 10 Female Night Feeding 95 Female Night Mating 8 Female Night Resting 175 Female Day Exploring 45 Female Day Interacting 6 Female Day Feeding 10 Female Day Mating 4 Female Day Resting 406 ImmatureNight Exploring 186 ImmatureNight Interacting 15 ImmatureNight Feeding 175 ImmatureNight Resting 200 ImmatureDay Exploring 68 ImmatureDay Interacting 8 ImmatureDay Feeding 6 __ 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 commented, minimal, self-contained, reproducible code.
Re: [R] question about chi values GLM
The column labeled Deviance pretty much _is_ the chi-square, specifically the likelihood ratio test statistic, which has an asymptotic chi-square distribution. (Using test=Rao gives you the alternative Rao efficient score test, which in your case doesn't make much of a difference.) Notice though, that those displays are sequential and it is not clear that the one in the image you attach is made in the same way (or in a sensible way for that matter). In particular, you have highly significant interaction terms, in which case the main effects tests are mostly irrelevant. You may need to consult a textbook on Poisson modelling or generalized linear modelling -- the discussion is a bit too long to be fitted into a mailing list. -pd On 14 Jun 2014, at 10:01 , Luis Fernando García luysgar...@gmail.com wrote: Dear all, I am making an analysis using a GLM using three explanatory variables and a response variable. I need to obtain a table similar to this one, http://postimg.org/image/5sau79wlt/r nevertheless, I have not been able to do it. I am having a hard time specially getting the chi square values. I would like to know how to obatin them. I have used the function ANOVA, but it shows me the deviance but not the Chi-Square values, can be used these values? I also would like to know what function could help me to make ad hoc comparisons for single variables and interactions. If any of you knows how to do both estimations, I would really appreciate it. All the best!!! This is my script a=read.table(ricis3.txt,header=T) attach(a) model7=glm(Count~Sex+Time+Behaviour+Sex*Time+Sex*Behaviour+Time+Behaviour*Sex,family=poisson) summary(model7) anova(model7,test=Chi) ricis3.txt__ 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 commented, minimal, self-contained, reproducible code. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd@cbs.dk Priv: pda...@gmail.com __ 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 commented, minimal, self-contained, reproducible code.
Re: [R] question about chi values GLM
On 14/06/2014 09:45, peter dalgaard wrote: The column labeled Deviance pretty much _is_ the chi-square, specifically the likelihood ratio test statistic, which has an asymptotic chi-square distribution. (Using test=Rao gives you the alternative Rao efficient score test, which in your case doesn't make much of a difference.) Notice though, that those displays are sequential and it is not clear that the one in the image you attach is made in the same way (or in a sensible way for that matter). In particular, you have highly significant interaction terms, in which case the main effects tests are mostly irrelevant. You may need to consult a textbook on Poisson modelling or generalized linear modelling -- the discussion is a bit too long to be fitted into a mailing list. We do not know what is meant by the entries in those tables. Many years ago (before even the term 'deviance' was coined) H.O. Lancaster and others partitioned chi-squared tests, with a similar table to an analysis of deviance but different numerical quantities. Although Peter's guess is the most likely one, it is not the only possible one. As an overall test of fit in a Poisson log-linear model there is a likelihood-ratio aka deviance test (sometimes called a G^2 test or G-test) and a Chi-squared test (which is different). The 'df' in the table make no sense. For three binary variables, Season x sex has more df than Season or Sex, and Time x Sex has fewer Even if we had the reference (and the OP really should have given us that to allow him to reproduce it under 'fair use' copyright law) I guess we would be little the wiser. -pd On 14 Jun 2014, at 10:01 , Luis Fernando García luysgar...@gmail.com wrote: Dear all, I am making an analysis using a GLM using three explanatory variables and a response variable. I need to obtain a table similar to this one, http://postimg.org/image/5sau79wlt/r nevertheless, I have not been able to do it. I am having a hard time specially getting the chi square values. I would like to know how to obatin them. I have used the function ANOVA, but it shows me the deviance but not the Chi-Square values, can be used these values? I also would like to know what function could help me to make ad hoc comparisons for single variables and interactions. If any of you knows how to do both estimations, I would really appreciate it. All the best!!! This is my script a=read.table(ricis3.txt,header=T) attach(a) model7=glm(Count~Sex+Time+Behaviour+Sex*Time+Sex*Behaviour+Time+Behaviour*Sex,family=poisson) summary(model7) anova(model7,test=Chi) ricis3.txt__ 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 commented, minimal, self-contained, reproducible code. -- Brian D. Ripley, rip...@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ 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 commented, minimal, self-contained, reproducible code.
