I'm not sure how returning an incorrect result is ever a 'positive' feature but at least the documentation could more clearly warn users that this method behaves differently in these cases -- summary(rock[,1]) vs summary(rock[,1:2]) -- and that the method can and does return incorrect results without any warning messages.   

I would encourage anyone teaching introductory R to look at the 'epicalc' package.  The re-vamped function 'summ' in that package returns correct results regardless - summ(rock), summ(rock$area).  In addition, when you only ask for one column you not only get the correct results, you also get a bonus distribution plot.  

I'd would like all of our students to use R, but little things like this are huge stumbling blocks for them. 
-jeanne 



	[[alternative HTML version deleted]]

