I agree with Tim and John. I covered those grouped distributions half-heartedly the first time I taught stats, in 1988, and haven't touched 'em since. It seems pretty shady (the implication that you're finding some nice specific number despite the unreasonable assumptions), and it's VERY low on the list of things they're likely to ever use again. Besides all of that, students hate it, and it makes them hate the other, much more useful stuff as well.
I do make students do calculations by hand (median, sd, etc.) on raw data despite the fact that they'll usually use SPSS to compute those things. I do it because I strongly believe that they should know where the numbers come from even when using a computer to get 'em. But I assume that also means that they're not likely to encounter much in the way of grouped data. Sure, I can think of some situations in which they might (secondary analyses of previously grouped data), but I've noticed that those things seem to make students thing that it's _desirable_ to group data, even when there is no reason to do so. When they design surveys, students tend to want to ask age or number of children (for example) using ranges (which is just simply wrong, in my opinion, given that people can easily tell you their exact age or number of children, so you get good data). When they code good data (exact number of children, for example), they STILL want to come up with ranges (in short, to simply throw away good data, by created grouped data). I'm in favor of doing whatever I can to nip that whole thing in the bud, and ignoring the whole grouped data thing seems like a good place to start. (let the stoning begin... <grin>) Paul Smith Alverno College Milwaukee --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
