Re: [R] Fixed zeros in tables
A.R. Criswell [EMAIL PROTECTED] wrote: Hello Andrew Robinson and R-List Thanks, Andrew, but this does not work. Puttting zero weights on structural zeros, one's elsewhere in glm() does not deliver the appropriate expected cell counts loglm() provides as one would expect. If you run the code provided below, you'll see loglm() delivers zero cell counts with loglm() but using glm() with the weights you suggest, the expected cell counts are not zero. Still hoping for a resolution. Andrew Criswell Associate Professor Hedmark University Postboks 104, Rena 2510, NORWAY If they are structural zeros, I believe you want: glm(COUNT ~ CONCERNS + AGE + GENDER, data=health, subset=(WEIGHTS0), family=poisson) David Duffy. -- | David Duffy (MBBS PhD) ,-_|\ | email: [EMAIL PROTECTED] ph: INT+61+7+3362-0217 fax: -0101 / * | Epidemiology Unit, Queensland Institute of Medical Research \_,-._/ | 300 Herston Rd, Brisbane, Queensland 4029, Australia GPG 4D0B994A v __ R-help@stat.math.ethz.ch 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] Fixed zeros in tables
Hello Andrew Robinson and R-List Thanks, Andrew, but this does not work. Puttting zero weights on structural zeros, one's elsewhere in glm() does not deliver the appropriate expected cell counts loglm() provides as one would expect. If you run the code provided below, you'll see loglm() delivers zero cell counts with loglm() but using glm() with the weights you suggest, the expected cell counts are not zero. Still hoping for a resolution. Andrew Criswell Associate Professor Hedmark University Postboks 104, Rena 2510, NORWAY -- ## Fienberg, The Analysis of Cross-Classified Contingency Tables, 2nd ed., p.148. ## Results from survey of teenagers regarding their health concerns. health - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(4, 0, 42, 57, 2, 0, 7, 20, 9, 4, 19, 71, 7, 8, 10, 21), WEIGHTS = c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) health.tbl - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = health) zeros - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) zeros - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = zeros) library(MASS) fm.1 - loglm(~ CONCERNS + AGE + GENDER, data = health.tbl, start = zeros, fitted = TRUE) fm.1; round(fm.1$fitted, 1) fm.3 - glm(COUNT ~ CONCERNS + AGE + GENDER, data = health, weights = health$WEIGHTS, family = poisson) fm.3.fit - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= fm.3$fitted) round(xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = fm.3.fit), 1) __ R-help@stat.math.ethz.ch 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] Fixed zeros in tables
Hello Andrew, I'm not sure how this is a problem. You can multiply the fitted values by the weights again, if you wish, or ignore the structural zeros altogether. The other predicted values all seem to me to be the same. I think that is a feature. Sometimes the goal for glm with structural zeros is to estimate those values that are missing. You are at liberty to ignore them. Cheers Andrew On Mon, Nov 27, 2006 at 02:47:01AM +0700, A.R. Criswell wrote: Hello Andrew Robinson and R-List Thanks, Andrew, but this does not work. Puttting zero weights on structural zeros, one's elsewhere in glm() does not deliver the appropriate expected cell counts loglm() provides as one would expect. If you run the code provided below, you'll see loglm() delivers zero cell counts with loglm() but using glm() with the weights you suggest, the expected cell counts are not zero. Still hoping for a resolution. Andrew Criswell Associate Professor Hedmark University Postboks 104, Rena 2510, NORWAY -- ## Fienberg, The Analysis of Cross-Classified Contingency Tables, 2nd ed., p.148. ## Results from survey of teenagers regarding their health concerns. health - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(4, 0, 42, 57, 2, 0, 7, 20, 9, 4, 19, 71, 7, 8, 10, 21), WEIGHTS = c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) health.tbl - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = health) zeros - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) zeros - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = zeros) library(MASS) fm.1 - loglm(~ CONCERNS + AGE + GENDER, data = health.tbl, start = zeros, fitted = TRUE) fm.1; round(fm.1$fitted, 1) fm.3 - glm(COUNT ~ CONCERNS + AGE + GENDER, data = health, weights = health$WEIGHTS, family = poisson) fm.3.fit - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= fm.3$fitted) round(xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = fm.3.fit), 1) -- Andrew Robinson Department of Mathematics and StatisticsTel: +61-3-8344-9763 University of Melbourne, VIC 3010 Australia Fax: +61-3-8344-4599 http://www.ms.unimelb.edu.au/~andrewpr http://blogs.mbs.edu/fishing-in-the-bay/ __ R-help@stat.math.ethz.ch 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.
[R] Fixed zeros in tables
Hello All R Users, Function loglm() in library MASS can be cajoled to accomodate structural zeros in a cross-classification table. An example from Fienberg demonstrates how this can be done. My question is: Can the function glm() perform the same task? Can glm() estimate a log-linear model with fixed zeros like loglm()? Thanks for your help, Andrew ## Fienberg, The Analysis of Cross-Classified Contingency Tables, 2nd ed., p.148. ## Results from survey of teenagers regarding their health concerns. health - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(4, 0, 42, 57, 2, 0, 7, 20, 9, 4, 19, 71, 7, 8, 10, 21)) health - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = health) zeros - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) zeros - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = zeros) library(MASS) fm.1 - loglm(~ CONCERNS + AGE + GENDER, data = health, start = zeros, fitted = TRUE) fm.1; round(fm.1$fitted, 1) __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Fixed zeros in tables
Hi Andrew, try the weights argument - apply zero weight to the structural zeros, and 1 elsewhere. Cheers Andrew On Sun, Nov 26, 2006 at 11:39:39AM +0700, A.R. Criswell wrote: Hello All R Users, Function loglm() in library MASS can be cajoled to accomodate structural zeros in a cross-classification table. An example from Fienberg demonstrates how this can be done. My question is: Can the function glm() perform the same task? Can glm() estimate a log-linear model with fixed zeros like loglm()? Thanks for your help, Andrew ## Fienberg, The Analysis of Cross-Classified Contingency Tables, 2nd ed., p.148. ## Results from survey of teenagers regarding their health concerns. health - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(4, 0, 42, 57, 2, 0, 7, 20, 9, 4, 19, 71, 7, 8, 10, 21)) health - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = health) zeros - data.frame(expand.grid(CONCERNS = c(sex, menstral, healthy, nothing), AGE = c(12-15, 16-17), GENDER = c(male, female)), COUNT= c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) zeros - xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = zeros) library(MASS) fm.1 - loglm(~ CONCERNS + AGE + GENDER, data = health, start = zeros, fitted = TRUE) fm.1; round(fm.1$fitted, 1) __ R-help@stat.math.ethz.ch 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. -- Andrew Robinson Department of Mathematics and StatisticsTel: +61-3-8344-9763 University of Melbourne, VIC 3010 Australia Fax: +61-3-8344-4599 http://www.ms.unimelb.edu.au/~andrewpr http://blogs.mbs.edu/fishing-in-the-bay/ __ R-help@stat.math.ethz.ch 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.
