Quiz Over Chapter 12 of the
6^{th} Edition
Post Hoc and Planned Comparisons
Introduction
 (T/F) With 3 comparison groups, Ho, if false, might be
false because m1 = m2
while m3 is equal to something
else.
 (T/F) Researchers use planned comparisons more often than they do
post hoc comparisons.
Post Hoc Comparisons: Definition and Purpose
 (T/F) There is confusion among researchers as to what is or is not
a post hoc test.
 What's the statistical focus of a post hoc test that's conducted
in connection with a oneway ANOVA?
 (T/F) Post hoc tests are used when the Ho of a oneway
analysis of variance is not rejected.
Post Hoc Comparisons: Terminology
 A post hoc test is sometimes referred to as a ______ test or a ______
test or an ______ test.
 Within the post hoc tests, what's a oneword synonym for "comparison"?
 (T/F) The F that comes from a oneway ANOVA can be referred to as
the "omnibus Ftest."
 If all possible "pairwise" comparisons are conducted between the means of
6 different groups, how many different comparisons will be made?
 Suppose we have 3 groups: undergrads, grad students in an M.S. program,
& grad students in a Ph.D. program. If the 2 groups of grad
students are combined and compared against the undergrads, this is a
_____ comparison.
Post Hoc Comparisons: Test Procedures Frequently Used
 Who invented the multiple comparison test that goes by the name "HSD"?
 Who invented the multiple comparison test that's called the "New
Multiple Range Test"?
 Which of the 5 tests used most often to do post hoc comparisons is
most "liberal"? Most "conservative"?
 Which of these testsDuncan, Tukey, NewmanKeuls protects most
against Type I errors? Type II errors?
 What is the name of the multiple comparison test that compares experimental
groups versus the control group (but doesn't compare experimental groups
against each other)?
Post Hoc Comparisons: The Null Hypothesis
 (T/F) A separate Ho exists for every comparison that's
set up in a post hoc investigation.
 In Excerpt 12.13, how many post hoc null hypotheses were there?
Post Hoc Comparisons: Presentation of Results
 (T/F) Pairwise comparisons can be accomplished via Tukey's HSD procedure
. . . but cannot be accomplished by the Tukey a or Tukey B procedures.
 In Excerpt 12.12, how many Tukey tests are being summarized?
 Suppose a Tukey test is used to make all pairwise comparisons among
4 means. Suppose further that these tests indicate that (a) the largest
mean is signifficantly larger than the secondlargest mean, (b) each
of those means is significantly different from the other 2 means, and
(c) the 2 smallest means are not significantly different from each
other. If the "reporting scheme" used in Table 4 of Excerpt
12.14 is used to summarize these results, how many different letters
would appear next to the sample means?
 Look at Excerpt 12.12. If we let "1" represent the heavy metal music group, "2" represent
the classical music group, and "3" represent the pop music group, which of the
following statements accurately summarizes the findings of the post hoc comparisons?
 1<2,3
 1>3>2
 3<2=1
 1>2,3
Post Hoc Comparisons: The Bonferroni Procedure as a Post Hoc Technique
 What a would be needed if the Bonferroni
technique were to be used by a ".05" researcher who wants to conduct
a post hoc analysis wherein all possible pairwise comparisons are made
among 5 groups?
Planned Comparisons
 (T/F) Planned comparisons are turned to by the researcher if the
ANOVA F turns out p > .05.
 (T/F) Since test procedures such as Tukey's were invented for use
as post hoc investigations, they can't be used in situations where the
researcher wants to conduct planned comparisons.
 A planned contrast is sometimes referred to as a ________ contrast.
 Return to question #2 and answer it again with these two changes:
(a) insert the words "ought to" after the word "Researchers" and (b)
delete the final 3 words of the sentence.
 (T/F) The planned comparisons set up by most researchers are nonpairwise
(rather than pairwise) in nature.
 (T/F) In any given study having three or more comparison groups,
the researcher can set up some planned comparisons that are nonpairwise
in nature
along with other planned comparisons that are pairwise in nature?
Comments
 If a planned comparison is set up to contrast one group's mean against
the average of two other groups (that have been lumped together), what
will the Ftest's first df number be?
 (T/F) The term "orthogonal" means "independent."
 (T/F) The equal variance assumption is important when a researcher
conducts an omnibus Ftest but it is not important if he/she
performs a planned or post hoc investigation.
 If three samples have means of 12.15, 18.50, and 21.75, the index d would turn
out to be smallest for a comparison of which 2 means?
 (T/F) All of the test procedures developed for doing post hoc and
planned comparisons have a builtin "control mechanism" that prevents
the results from being statistically significant if there's no practical
significance.
 In Excerpt 12.20, results are presented for a oneway ANOVA and a set of pairwise
post hoc comparisons. There were 4 groups in this study, and the sample means for 3 of
these groups are presented in the excerpt. The sample mean that is not shown in the excerpt
might have been equal to ___.
 10.00
 9.40
 8.00
 7.60
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