Dear All:
I have a question concerning pairwise comparisons between four treatment
conditions. My experience is mostly with ANOVA, and (I think!) I can
understand the reasoning for the use of multiple comparison procedures
(e.g., Duncan's, Tukey's, or LSD) instead of individual t-tests between
conditions.
I assume the case is the same with my current problem: I have a single
-factor experiment with four levels of the factor (treatment conditions)
and a discrete dependent measure (pass/fail), resulting in a 2 x 4
contingency table. I have used a Chi-Sq. analysis to determine if there is
a statisitcally significant difference between the (treatment) groups (all
4!), and indeed there is. I assume, however, that I cannot simply do
pairwise comparisons between the groups using Chi-Sq. and 2 x 2 matrices
without inflating the probability of Type 1 error, (1-alpha)^4 in this
case. As far as I know, there are no equivalents to Duncan's or Tukey's
tests for the type of data (binary) I have to deal with.
I would appreciate if anyone would confirm my reasoning above and offer any
advice on how to proceed with the analysis of pairwise differences in the
case of categorical (dichotomous) data. References to relevant literature
would also be welcome!
Best,
Esa
____________________________
Esa M. Rantanen, Ph.D.
Assistant Professor
University of Illinois at Urbana-Champaign
Institute of Aviation, Aviation Human Factors Division
Aviation Research Laboratory, Q5, MC-394
One Airport Road, Willard Airport
Savoy, IL 61874
Tel. 217-244-8657 (ARL)
Tel. 217-244-7397 (Psych.)
Tel. 217-373-8276 (Home)
Fax 217-244-8647
e-mail: [EMAIL PROTECTED]
url: http://www.aviation.uiuc.edu
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