This will probably seem very simple to experienced R programmers: I am doing a snp association analysis and am at the model-fitting stage. I am using the Stats package's "drop1" with the following code: ##geno is the dataset ## the dependent variable (casectrln) is dichotomous and coded 0,1 ## rs743572_2 is one of the snps (which is coded 0,1,2 for the 3 genotypes)
library(stats) modadd = glm(geno$casectrln ~rs743572_2 + factor(racegrp)+ factor(smokgp)+ factor(alcgp)+ factor(bmigp) + factor(ipssgp) + agebase, family="binomial") drop1(mod,scale=0,test=c("Chisq"), x=NULL, k=2) There is a great deal of missing data in this dataset for both snps and for covariates--so I have been instructed not to simply drop all cases with missing genotype or covariate data . How can I drop the observations which are missing only for the snp I am modeling at the time, then reinstate those observations to model the next snp? Thanks for any help, Nora [[alternative HTML version deleted]] ______________________________________________ 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.