A researcher conducted an experiment on the effects
of a new drug on depression. The
researcher had a control group that received nothing, a placebo group, and an
experimental group that received the drug.
A depression inventory that provided a measure of depression on a 50
point scale was used (50 indicates that an individual is very high on the
depression variable). The ANOVA summary
table appears next, along with the mean depression score for each condition.
Source Df SS MS F
Drug condition Mean n
Control 36.26 15
Placebo 33.33 15
Drug 24.13 15
the ANOVA summary table
Fobt significant at a = .05; at a = .01?
post hoc comparisons if necessary.
conclusion can be drawn from the F-ratio and the post hoc comparisons?
is the effect size, and what does this mean?