Deck 15: Introduction to the Analysis of Variance

Question 1

The alternative hypothesis evaluated by F _obt in the one-way ANOVA states that _________.

A) all conditions have the same effect
B) one or more of the conditions have different effects
C) µ 1 = µ 2 = u 3 = µ k
D) µ 1 ≠ µ 2 ≠ µ 3 ≠ µ k
E) b and d

Answer 1

one or more of the conditions have different effects

Question 2

As the differences between the group means increases, _________.

A) MS_between increases
B) F _obt decreases
C) t _obt decreases
D) all of these
E) none of the above

Answer 2

MS_between increases

Question 3

Which of the following is(are) true?

A) df for MS_within = N - k
B) df for MS_between = k - 1
C) df total = N - 1
D) all of these

Answer 3

all of these

Question 4

The null hypothesis in the one-way ANOVA asserts that _________.

A) the within groups variance estimate is an estimate of the population variance
B) µ 1 = µ 2 = µ 3 = µ k
C) the between group variance estimate and the within group variance estimate are both estimates of the same population variance
D) the within group sum of squares is equal to the between group sum of squares
E) µ 1 = µ 2 = µ 3 = µ k and the between group variance estimate and the within group variance estimate are both estimates of the same population variance

Question 5

The one-way ANOVA partitions the total variability into _________.

A) ΣS_within and ΣS _between
B) MS_within and MS_between
C) ΣS_within and ΣS _total
D) ΣS _between and MS_between

Question 6

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. MS_between = _________.

A) 48.250
B) 50.145
C) 51.254
D) 45.750

Question 7

Which of the following is (are) assumption(s) underlying the use of the F test?

A) the raw score populations are normally distributed
B) the variances of the raw score populations are the same
C) the mean of the populations differ
D) the raw score populations are normally distributed and the variances of the raw score populations are the same
E) all of these

Question 8

If df _between = 2 and df _within = 14, using a = 0.05, F _crit = _________.

A) 19.42
B) 4.60
C) 3.74
D) 6.51

Question 9

The F ratio increases as _________.

A) the variability between means increases relative to the variability within groups
B) the variability between means decreases relative to the variability within groups
C) the total variability increases
D) the total variability decreases
E) the variability within groups remains the same

Question 10

If its assumptions are met, the analysis of variance technique is appropriate when _________.

A) two or more factors are varied
B) several levels of a single independent variable are compared
C) three or more groups are involved
D) all of these

Question 11

Which of the following increase(s) as the difference between the group means increases?

A) MS _between
B) F _obt
C) t _obt
D) all of these

Question 12

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. ΣS_within = _________.

A) 62.25
B) 59.75
C) 56.65
D) 57.00

Question 13

The parameter being estimated in the analysis of variance is the ________.

A) sample mean
B) variance of the H 0 populations
C) sample variance
D) mean of the H 0 populations
E) F _obt

Question 14

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. ΣS _between = _________.

A) 94.2
B) 96.0
C) 96.5
D) 97.4

Question 15

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. MS_within = _________.

A) 6.813
B) 6.558
C) 6.702
D) 6.639

Question 16

A major limitation of a two group design is that _________.

A) we can't run enough subjects
B) very often, two groups are insufficient for a clear interpretation
C) the population parameters may not be applicable
D) the means between groups may not differ

Question 17

Which of the following would cause F _obt to increase?

A) an increase in the difference between the means
B) an increase in the within-groups variability
C) an increase in the magnitude of the independent variable's effect
D) an increase in the difference between the means and an increase in the within-groups variability
E) an increase in the difference between the means and an increase in the magnitude of the independent variable's effect

Question 18

MS_between is a measure of _________.

A) s 2 alone
B) s 2 + the effects of the independent variable
C) the variability between the means
D) b and c

Question 19

If ΣS_total = 20 and ΣS _between = 14, ΣS_within = _________.

A) 34
B) 6
C) - 6
D) need more information

Question 20

When analyzing data from experiments that involve more than two groups _________.

A) doing t tests on all possible pairs of means decreases the probability of making Type I errors
B) doing t tests on all possible pairs of means increases the probability of making Type I errors
C) it is generally permissible to do t tests between all possible pairs of means and use Student's t distribution
D) doing t tests on all possible pairs of means increases the probability of making Type II errors

Question 21

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. F _obt = _________.

A) 10.21
B) 8.44
C) 8.20
D) 6.88

Question 22

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. MS_between = _________.

A) 14.30
B) 13.76
C) 13.07
D) 11.84

Question 23

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Using a = 0.05, what do you conclude?

A) reject H 0 ; the drug has the same effect on memory at all levels
B) reject H 0 ; the drug does not have the same effect on memory at all levels
C) retain H 0 ; we cannot conclude that the drug affects memory
D) accept H 0 ; the drug has no effect on memory

Question 24

Which of the following is(are) illegal values for F _obt?

A) 1.00
B) 0.96
C) - 2.97
D) b and c

Question 25

What is the value of F _crit for an experiment with k = 3, n 1 = n 2 = n 3 = 10 subjects, and a = 0.01?

A) 5.45
B) 4.51
C) 3.35
D) 5.49

Question 26

The total degrees of freedom for an experiment with n 1 = 10, n 2 = 12, and n 3 = 10 is ________.

A) 2
B) 32
C) 31
D) 29

Question 27

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. SS_within = _________.

A) 19.60
B) 16.80
C) 18.80
D) 22.80

Question 28

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Using a = 0.05, what do you conclude?

A) reject H 0 ; there is no difference among the treatments
B) reject H 0 ; at least one of the treatments differs from at least one of the others
C) retain H 0 ; we cannot conclude that there is a difference among the treatments
D) accept H 0 ; we cannot conclude that there is a difference among the treatments

Question 29

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Using a = 0.05, F _crit = _________.

A) 3.98
B) 19.41
C) 6.93
D) 3.88

Question 30

What is the value of F _obt?

A) 5.67
B) 6.53
C) 1.95
D) 3.26

Question 31

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Estimate the size of the effect. = _________

A) 0.5226
B) 0.4824
C) 0.4393
D) 0.4658

Question 32

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. F _obt = _________.

A) 8.31
B) 7.30
C) 7.27
D) 6.45

Question 33

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. SS _between = _________.

A) 27.53
B) 26.13
C) 23.67
D) 28.60

Question 34

What is your conclusion? Again use a = 0.05.

A) retain H ₀
B) reject H ₁
C) reject H ₀
D) accept H ₀

Question 35

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. MS_within = _________.

A) 1.40
B) 1.90
C) 1.57
D) 1.88

Question 36

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Estimate the size of the effect. ç ² = _________.

A) 0.5530
B) 0.5034
C) 0.6232
D) 0.5341

Question 37

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Estimate the size of the effect. = _________.

A) 0.5109
B) 0.5210
C) 0.5100
D) 0.4328

Question 38

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Using a = 0.05, F _crit = _________.

A) 8.02
B) 4.26
C) 19.38
D) 4.46

Question 39

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Estimate the size of the effect. ² = __________.

A) 0.6524
B) 0.6176
C) 0.6318
D) 0.6034

Question 40

What is the value of F _crit ? Use a = 0.05.

A) 5.14
B) 4.76
C) 4.46
D) 4.07

Question 41

The HSD test _________.

A) is used for planned comparisons
B) maintains the Type I error rate at alpha
C) is used for a post hoc comparisons
D) maintains the Type I error rate at alpha and is used for a post hoc comparisons

Question 42

If s 12 = 10, s 22 = 15, and s 32 = 12, and n 1 = n 2 = n 3 , then MS_within equals _________.

A) cannot be determined from information given
B) 37.0
C) 12.33
D) 3.51

Question 43

If = 46, = 50, = 92 and n 1 = n 2 = n 3 , what is the value of ?

A) cannot be determined from information given
B) 50.0
C) 188.0
D) 62.67

Question 44

Using ², what is the estimated size of effect?

A) 0.7232
B) 0.6852
C) 0.6582
D) 0.6312

Question 45

If s 12 = 9, s 22 = 6, s 32 = 8, and n 1 ≠ n 2 ≠ n 3 , then MS_within equals _________.

A) cannot be determined from information given
B) 7.667
C) 2.77
D) 23.0

Question 46

Which of the following is(are) statistical test(s) for doing post hoc comparisons?

A) HSD test
B) Scheffé test
C) independent t test
D) two group one-way ANOVA
E) HSD test and independent t test

Question 47

A posteriori or post hoc comparisons _________.

A) are planned before the experiment
B) are often decided on after the data are collected
C) require a significant F _obt before they may be conducted
D) are often decided on after the data are collected and require a significant F _obt before they may be conducted
E) all of these

Question 48

Using the HSD test, if there are 16 df associated with MS_within , and a = .05 and the number of groups = 3, Q _crit = _________.

A) 4.13
B) 3.00
C) 3.65
D) 4.79

Question 49

Using , the estimated size of effect is _________.

A) 22.6% of the variability
B) 52.8% of the variability
C) 43.6% of the variability
D) 55.1% of the variability

Question 50

If MS_between = 27.9 and MS_within = 54.2, what is the value of F _obt?

A) impossible result, there must be an error
B) 1.94
C) 0.51
D) 2.76

Question 51

What is the value of ΣS_total if ΣS_between = 236 and ΣS_within = 54?

A) 290
B) 182
C) 4.37
D) 100

Question 52

In doing planned comparisons, we use _________.

A) the t test for independent groups, unaltered
B) the t test for independent groups with MS_within in the denominator
C) df equal to those of MS_within
D) the t test for independent groups with MS_within in the denominator and df equal to those of MS_within

Question 53

By doing multiple t tests when there are more than 2 experimental groups we increase the risk of making what kind of mistake?

A) accepting H₀
B) Type I error
C) Type II error
D) all of these

Question 54

Using the Scheffé test, the appropriate critical value = _________.

A) F _crit taken from the entire ANOVA
B) F _crit taken from the 2 groups being compared
C) t _crit using the df taken from the entire ANOVA
D) t _crit using the df taken from the 2 groups being compared

Question 55

If df between = 3 and df total = 29 and F _obt = 3.15, what would you conclude using a = 0.05?

A) reject H₀
B) reject H₁
C) retain H₀
D) retain H₁

Question 56

If SS_within = 126, N = 28, k = 4, then what is the value of MS_within ?

A) cannot be determined from information given
B) 5.25
C) 42.0
D) 4.667

Question 57

If k = 2 and t _obt = 2.95, what would the value of F _obt be for an independent groups design?

A) 2.95
B) 8.70
C) 1.72
D) 0.05

Question 58

A priori comparisons _________.

A) are planned in advance of the experiment
B) often arise out of theory and prior research
C) may be done without obtaining a significant F obt in the one-way ANOVA
D) all of these

Question 59

If SS_total = 96, SS_within = 47, and SS _between = 68, what would you conclude?

A) reject H₀
B) retain H₀
C) cannot be determined from information given
D) there must be an error in the calculations

Question 60

When doing planned comparisons, _________.

A) there is no correction for the inflated Type I error probability
B) a different number of df are used which corrects for the inflated Type I error probability
C) t obt is reduced to correct for the inflated Type I error probability
D) a different sampling distribution is used to correct for the inflated Type I error probability

Question 61

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Using a = .05, what do you conclude?

A) retain H 0 ; we cannot conclude the drug has a different effect at these levels
B) reject H 0 ; the drug has different effects at these levels
C) retain H 0 ; the drug has the same effect at these levels
D) reject H 0 ; the groups are not significantly different

Question 62

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Assume you are doing planned comparisons, using a = .05. The critical value is _________.

A) ± 2.262
B) - 1.833
C) ±2.228
D) 3.95
E) 3.20

Question 63

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Doing planned comparisons, using a = 0.05, the critical value is _________.

A) ± 2.179
B) - 1.782
C) ±2.681
D) 2.145

Question 64

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Assume you are doing planned comparisons evaluating drug levels 2 and 3 using a = 0.05 and H 1 is nondirectional. What is your conclusion?

A) accept H 0 ; the drug has the same effect at these levels
B) retain H 0 ; we cannot conclude the drug has a different effect at these levels
C) reject H 0 ; the groups are not significantly different
D) reject H 0 ; the drug has different effects at these levels

Question 65

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Assume you are doing post hoc testing between drug levels 2 and 3 using the Scheff test. Given the following values obtained from the ANOVA: , , , n ₁ = n ₂ = n ₃ = 4, k = 3, df _between = 2, df _within = 9, MS_within = 6.639, the value of SS _{between ( groups i and j)} = _________.

A) 78.125
B) 66.125
C) 0.5000
D) 69.125

Question 66

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. The value of F _Scheff is _________.

A) 5.88
B) 5.21
C) 4.98
D) 0.04

Question 67

Doing multiple comparisons following a three group ANOVA with equal n in each group, the critical value of the inference test statistic changes from comparison-to-comparison in the _________.

A) t test for independent groups
B) HSD test
C) Scheffé test
D) all of these
E) none of thse

Question 68

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Using the HSD test with a = 0.05, the appropriate critical value is _________.

A) ±2.179
B) 3.08
C) 3.77
D) 5.05

Question 69

The value used in the Scheffé test to evaluate is _________.

A) the df computed on groups i and j
B) MS_within taken from the entire ANOVA
C) the df computed in planned comparisons
D) MS_{within ( groups i and j )}

Question 70

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Using the Scheff test with a = 0.05, F _crit = _________.

A) 6.99
B) 3.86
C) 8.02
D) 4.26

Question 71

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. The value of MS _{between ( groups i and j)} = _________.

A) 33.063
B) 39.062
C) 34.562
D) 0.2500

Question 72

The df used in the Scheffé test to compute is _________.

A) the df computed on the two groups being compared
B) the df _between taken from the entire ANOVA
C) the df computed in planned comparisons
D) the df _within taken from the entire ANOVA
E) the df computed in planned comparisons and the df _within taken from the entire ANOVA

Question 73

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. Assume you wanted to compare drug levels 2 and 3 using planned comparisons and a nondirectional H 1 . Given , , , n = 4, MS_within = 6.639, df _within = 9, df _between = 2, k = 3, the obtained value of the appropriate statistic is _________.

A) Q _obt = 4.46
B) t _obt = -3.16
C) t _obt = -3.15
D) t _obt = -0.55

Question 74

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Assume you wanted to compare cognitive/behavioral therapy with relaxation therapy, using planned comparisons and a nondirectional H 1 . The obtained value of the appropriate statistic is _________.

A) Q _obt = 3.15
B) t _obt= -2.29
C) t _obt = -2.22
D) t _obt = -0.55

Question 75

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Assume you are doing post hoc testing between cognitive behavioral therapy and relaxation therapy, using the Scheffé test. Given the following values obtained from the ANOVA: , , , n ₁ = n ₂ = n ₃ = 5, k = 3, df _between = 2, df _within = 12, MS_within = 1.900, the value of SS _{between ( groups i and j)} = _________.

A) 25.600
B) 173.333
C) 3.600
D) 10.000

Question 76

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Using the HSD test with a = .05, what is your conclusion?

A) retain H 0 ; we cannot conclude the two therapies differ in effectiveness
B) reject H 0 ; the two therapies appear to differ in effectiveness
C) retain H 0 ; the two therapies have the same effectiveness
D) reject H 0 ; the two therapies are not significantly different

Question 77

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Doing planned comparisons, using a = 0.05, what is your conclusion?

A) accept H 0 ; the two therapies are equal in effectiveness
B) retain H 0 ; we cannot conclude the two therapies differ in effectiveness
C) reject H 0 ; the groups are not significantly different
D) reject H 0 ; the two therapies appear to be differentially effective

Question 78

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. The appropriate df for doing planned comparisons = _________.

A) 11
B) 6
C) 9
D) 2

Question 79

A clinical psychologist is interested in comparing the effectiveness of short term relaxation and cognitive-behavioral therapy in treating mild depression. An experiment is conducted in which 15 patients with mild depression are randomly selected and assigned 5 each to a relaxation therapy group, a cognitive/behavioral therapy group, and an attention placebo group. Therapy is administered until the patient is judged no longer depressed or until 10 treatment sessions have elapsed. The following data is obtained. Scores are the number of sessions for each patient. Assume you are comparing cognitive/behavioral therapy with relaxation therapy, using the HSD test. The obtained value of the appropriate statistic is _________.

A) t _obt = - 2.23
B) Q _obt = 3.24
C) Q _obt = - 3.15
D) Q _obt = 5.25

Question 80

When doing multiple comparisons, which method is the most powerful?

A) planned comparisons
B) Scheffé test
C) the HSD test
D) they are all equally powerful