hello I need a clarification.
in logistic regression, saturated model having all combinations and interactions of variables should be constructed in this way ? : > rsat2=glm(cbind(landp,landa) ~ as.factor(rlito)*as.factor(rslp)*as.factor(rasp)*as.factor(rplc)*as.factor(rwi),family= binomial(link=logit),data=rdf46) then using stepAIC to eliminate some models having high AIC values. > stpAIC_r2=stepAIC(rsat2,list(lower=~1,upper=formula(rsat2)),trace=F) But obtained final model looks very intricate and I couldn't interpret it. > stpAIC_r2$anova Do I have to consider last line (13) ? 1 2 - as.factor(rlito):as.factor(rslp):as.factor(rasp):as.factor(rplc):as.factor(rwi) 3 - as.factor(rslp):as.factor(rasp):as.factor(rplc):as.factor(rwi) 4 - as.factor(rlito):as.factor(rslp):as.factor(rasp):as.factor(rwi) 5 - as.factor(rlito):as.factor(rslp):as.factor(rplc):as.factor(rwi) 6 - as.factor(rlito):as.factor(rslp):as.factor(rwi) 7 - as.factor(rlito):as.factor(rasp):as.factor(rplc):as.factor(rwi) 8 - as.factor(rlito):as.factor(rplc):as.factor(rwi) 9 - as.factor(rlito):as.factor(rslp):as.factor(rasp):as.factor(rplc) 10 - as.factor(rslp):as.factor(rasp):as.factor(rplc) 11 - as.factor(rlito):as.factor(rslp):as.factor(rplc) 12 - as.factor(rlito):as.factor(rasp):as.factor(rplc) 13 - as.factor(rlito):as.factor(rslp):as.factor(rasp) Df Deviance Resid. Df Resid. Dev AIC 1 NA NA 191 458.3157 3310.353 2 1 0.3148536 192 458.6305 3308.668 3 24 31.8915731 216 490.5221 3292.560 4 7 1.3523216 223 491.8744 3279.912 5 13 13.1002785 236 504.9747 3267.012 6 19 23.7270352 255 528.7017 3252.740 7 7 4.8455686 262 533.5473 3243.585 8 9 5.7980351 271 539.3453 3231.383 9 8 7.9086994 279 547.2540 3223.292 10 40 50.8028626 319 598.0569 3194.095 11 17 12.8919748 336 610.9489 3172.987 12 14 8.1175215 350 619.0664 3153.104 13 18 27.9371216 368 647.0035 3145.041 I will be appreciate if you explain. regards Ahmet Temiz -- Open WebMail Project (http://openwebmail.org) -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ______________________________________________ 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.