This must be a really trivial question but I'm struggeling to get a solution. Here is my problem:
this works
#I run a simple regression
data(mtcars)
dataf <- mtcars
summary(fit1 <- lm(mpg ~ wt, data=dataf))
#Then I merge the fitted values with the data frame
dataf$fit <- fitted(fit1)
This (of course) doesn't work
dataf[2,]<-NA
summary(fit2 <- lm(mpg ~ wt, data=dataf))
#of course the NA value reduces my lm output
dataf$fit2 <- fitted(fit2)
Error in `$<-.data.frame`(`*tmp*`, "fit2", value = c(23.3189679389035, :
replacement has 31 rows, data has 32
but how do I geht the second example to work? I tried a solution via the row.names in model.matrix() but this does not work when I include certain factors in my regression (this has been reported as a bug if I understand this correctly). Thank you for your kind help!