I've never taught statistics, another thing I'm thankful for
(see my previous comment on pregnancy).
But there are three specific, widely neglected topics that I wish
people who do teach statistics would give some attention to.
Especially when their treatment supports my own views on these
topics, as follows:
1) Planned vs post-hoc "shotgun" approaches to pairwise
comparisons.
We should be encouraging students to consider beforehand
the set of comparisons which are necessary and sufficient to
extract all needed information from an experiment, and then to
test only those comparisons (the planned as opposed to the
post-hoc "shotgun" approach).
2) Multiple comparisons
We should be warning students of the error of uncorrected
multiple comparisons, and instructing them how to mend their
ways. I recommend the Bonferroni, an intuitively easy-to-grasp,
easy to do, and universally applicable method. Its chief
drawback, alleged excessive conservatism, is actually an
advantage. Because the correction is more severe the more
comparisons are made, it encourages limiting comparisons to only
those which are truly meaningful. Moreover, its use would cut
down on findings which aren't.
3) One-tailed vs two-tailed tests
Having a directional hypothesis is insufficient justification for
the use of a one-tailed test. We should make students swear never
to use one-tailed tests except in very, very, special
circumstances.
-Stephen
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Stephen 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 Department web page at http://www.ubishops.ca/ccc/div/soc/psy
Check out TIPS listserv for teachers of psychology at:
http://www.frostburg.edu/dept/psyc/southerly/tips/
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