I have a contingency table with a 0/1 variable (fwr) that flags a particular condition, a weight variable (cnt) and other variables (e.g. zz) characterizing that observation of the table. I am trying to use GLM. By converting the variables to factors and running the following regression: fwr1<-factor(fwr) zz1<-factor(zz1) res1<-glm(fwr1 ~ zz1,weights=cnt) Is that appropriate? Paul M. Jacobson Jacobson Consulting Inc. 80 Front Street East, Suite 720 Toronto, ON, M5E 1T4 Voice: +1(416)868-1141 Farm: +1(519)463-6061/6224 Fax: +1(416)868-1131 E-mail: pmj at jciconsult.com Web: http://www.jciconsult.com/ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
>>>>> "PaulMJ" == Paul M Jacobson <pmj at jciconsult.com> >>>>> on Sat, 10 Aug 2002 15:02:55 -0400 writes:PaulMJ> I have a contingency table with a 0/1 variable (fwr) PaulMJ> that flags a particular condition, a weight variable PaulMJ> (cnt) and other variables (e.g. zz) characterizing PaulMJ> that observation of the table. I am trying to use PaulMJ> GLM. By converting the variables to factors and PaulMJ> running the following regression: PaulMJ> fwr1<-factor(fwr) PaulMJ> zz1<-factor(zz1) PaulMJ> res1<-glm(fwr1 ~ zz1,weights=cnt) (spaces around "<-" would improve readibility} PaulMJ> Is that appropriate? not quite. Assuming that you really want to predict (a function of) the probability P[ fwr = 1 | zz1 ] you need at least to add family = binomial to your glm() arguments. The thing you did above was least-squares regression with a 0/1 variable which is probably not what you wanted. Martin Maechler <maechler at stat.math.ethz.ch> http://stat.ethz.ch/~maechler/ Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27 ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND phone: x-41-1-632-3408 fax: ...-1228 <>< -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._