Consider
> summary(1:5)
Min. 1st Qu. Median Mean 3rd Qu. Max.
1 2 3 3 4 5
> summary(c(1:5,NA))
Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
1 2 3 3 4 5 1
Wouldn't it be more stringent if "NA's" was also reported in the first case??
Regards
Søren