Robert Herdegen asked about what kind of error bar is to be prefered, and Mike Scoles said:
> I don't know if there is a convention, but 1 standard error has always > made sense to me. If the error bars for two groups do not overlap, > you can be reasonably confident (but not certain) that the means are > significantly different. Nope. It's three error bars between the means, not two as Mike suggests and as most think. See Dunlap and May (1989). I like standard errors best, for two reasons: 1) shorter than other choices, hence less clutter on the graph 2) lend themselves well to eyeballing whether significant or not as above. In practice, I note the gap between the opposing error bars of the two groups, and estimate whether an average of the two will fit between. If yes, it will probably be significant at p = .05. Of course, the more the gap exceeds this minimum, the more it is likely. Stephen Dunlap, W. and May, J. (1988), Judging statistical significance by inspection of standard error bars. Bulletin of the Psychonomic Society, 27, 67-68. ___________________________________________________ Stephen L. Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Dept web page at http://www.ubishops.ca/ccc/div/soc/psy TIPS discussion list for psychology teachers at http://faculty.frostburg.edu/psyc/southerly/tips/index.htm _______________________________________________ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
