On Thu, 4 May 2006, Guojun Zhu wrote: > I am still battling with my project :( > > I have a line like this > > lm(month.model$next.ret~.,month.model,na.action=na.omit)
Yourexamplesmightactuallybereeadableifyouusedyourspacebar. next.ret ~ . would suffice here. > month.model is a data frame with lots of columns. One > of them is "Oth", a dummy variable. I checked > month.model, there are two rows with number 1 and > others are either 0 or NA. the two rows with Oth==1 > have no NA. I have totally about 900 rows. But after > the regression, the Oth's coefficient is NA. I do not > understand. You don't show us how you reach that conclusion, but probably aliasing is the cause. See ?alias. > Another issue is also about NA. I offen use something > like "model[model$Oth==1,]", but it will not only > gives rows with oth==1, but also gives some rows with > all item as NA. I then changed this into " > month.model[(month.model$Oth==1)&(!is.na(month.model$next.ret)),]" > and it gives the same result. Finally I change it > into > " > month.model[(month.model$Oth==1)&(!is.na(month.model$Oth)),]" > and it works. next.ret is a column for sure. Can > anyone explain this to me? You want month.model$Oth %in% 1 Such things are covered with detailed examples in chapter 2 of MASS4 (see the FAQ). -- Brian D. Ripley, [EMAIL PROTECTED] 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, UK Fax: +44 1865 272595 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
