Question

a. a researcher wishes to test the differences among five poplulaiton means, using .05 criterion of significance. Why is it a bad idea to perform 10 t tests for the 10 possible pairs of means?

b. in one-way analysis of variance, what can cause the group means to vary? how about The degrees of freedom for the numerator is equal to?

Answer #1

(a)

It is bad idea to perform 10 t tests for the 10 possible pairs of
means because the repetition of multiple tests repeatedly add
multiple chances of error, which result in a larger
level than the pre -set level, The
comparisons are repeated 10 times in an experiment and an
unacceptable increased total error rate of 1 - (1 - )^{10} is
expected for the total comparison procedure in the experiment.

(b) In one way Analysis of Variance, the difference in the relative size of variance among group means (between group variance) with the average variance within group )within group variance) cause the group means to vary.

(c) The degrees for the numerator = k - 1,

where k is the number of treatments.

What is the advantage of using ANOVA to test for differences
among treatment means rather than testing all possible pairs of
treatment means?

1.A researcher uses one-factor ANOVA to test the statistical
significance of differences among five treatments, with a sample of
n = 10 in each treatment group. The F-ratio for this analysis would
have what df values?
A. df = 5, 100
B. df = 4, 95
C. df = 4, 45
D. None of the above.
2. For a one-factor ANOVA comparing four treatment groups,
MSbetween = 32. What is the value of SSbetween?
A. 96
B. 80
C. 36...

1. The F ratio may be used to assess difference between
(among):
a. two sample means b. three sample means c. four sample means
d. All of these
3. With a two-group experimental design, the independent
variable has been manipulated at:
a. one level b. two levels c. three levels d. all of these
4. For the F ratio, if alpha is set at .05, it remains at .05 of
comparisons are made between (among)
a. 2 group means b....

Practice Exercise 13: One -way Analysis of Variance (ANOVA)
1. When is it appropriate to use a one-way ANOVA to analyze
data?
2. What letter is use the designate the test statistic used in
the one-way ANOVA?
3. What are the two types of variance that are examined when
conducting an analysis of variance?
4. Which type of variance is related to the effect of a
treatment?
5. Does the analysis of variance test differences between two
specific groups?
Use...

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Perform an analysis of variance and decide at the 0.01 level of
significance whether the differences among the four sample means
can be attributed to chance. State the conclusion.

A university also wants to determine if there are significant
differences in GPA among students from different majors. They
collect data on GPA for four different majors and find the
following results: Business Administration (M = 2.9; N = 60), Fine
Art (M = 3.3; N = 60), Nursing (M = 3.5; N = 60), and Psychology (M
= 3.6; N = 60). They also calculated the between-group and total
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(1) A Chi-squared test is typically used to test for any of the
following except which of the following?
(A) If a mathematical model accurately predicts our observed
frequencies of data values.
(B) If a mathematical model accurately predicts the total number
of observed data values.
(C) If a mathematical model accurately predicts the pattern of
our observed data values.
(D) Whether two factors present in a population are independent
of one another.
(E) Whether a series of populations experience...

T-tests are used when you want to examine differences but you do
not know everything about the population. There are three types of
t-tests that you may choose to do: one-sample t-test, independent
sample t-test, or dependent sample t-test. You can calculate these
by hand, in SPSS, or in Excel. The instructions below can be used
for SPSS and your textbook offers instructions for using Excel.
Single-sample t-tests
These tests are used when you want to determine the
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A researcher is interested in whether salaries for middle school
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The Data Analysis output for the various tests used when
comparing two group means are shown below. The significance level
was .05.
F-Test Two-Sample for Variances
Teachers
Nurses
Mean
45946.07
53365.13
Variance
68256753
86820446
Observations
300
300
df
299
299
F
0.7862
P(F<=f) one-tail
0.0190
F Critical one-tail
0.8265
t-Test: Paired Two...

10. Tukey’s HSD test
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Suppose researchers at a sleep clinic are interested in the
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