# Statistics in Psychology

1. A method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample, is called

random sampling

level of significance

hypothesis testing

guessing

2. The one-sample z test is a hypothesis test used to test hypotheses

concerning a single population with a known variance

concerning at least one population

concerning the variance in a population

all of the above

3. Given the following values: μ = 6.0, M = 7.6, n = 36, σ = 6, conduct a one-sample z test at a 0.05 level of significance. For a one-tailed test, upper-tail critical, what is the decision?

to reject the null hypothesis

to retain the null hypothesis

There is not enough information since the sample size is not given.

4. ________ allows researchers to describe (1) how far mean scores have shifted in the population, or (2) the percentage of variance that can be explained by a given variable.

significance

probability

power

effect size

5. The ________ is an inferential statistic used to determine the number of standard deviations in a t distribution that a sample means deviates from the mean value or mean difference stated in the null hypothesis.

distribution

statistic

standard error

degrees of freedom

6. State the critical value(s) for the following two-tailed t test at a 0.05 level of significance: t(∞).

±1.645

±1.96

the same as for a two-tailed z test at a 0.05 level of significance

both ±1.96 and the same as for a two-tailed z test at a 0.05 level of significance

7. A researcher reports that the mean time it takes to complete an experimental task is 1.4 ± 8.0 (M ± SD) seconds. If the null hypothesis was that the mean equals 1.0, then what is the effect size for this test using estimated Cohen’s d?

d = 0.05; small effect size

d = 0.50; medium effect size

d = 1.05; large effect size

There is not enough information to answer this question.

8. Computing a two-independent sample t test is appropriate when

different participants are assigned to each group

the population variance is unknown

participants are observed one time

all of the above

9. A researcher has participants rate the likability of a sexually promiscuous person described in a vignette as being male (n = 20) or female (n = 12). The mean likability ratings in each group were 4.0. If the null hypothesis is that there is no difference in likability ratings, then do likability ratings differ at a 0.05 level of significance?

Yes, this result is significant, p < 0.05.

No, this result is not significant, t(30) = 0.

No, this result is not significant, t(30) = 1.00.

There is not enough information to answer this question, because the variance in each sample is not given.

10. A type of related samples design in which participants are observed more than once is called a

repeated measures design

matched pairs design

matched samples design

both matched pairs design and matched samples design

11. A researcher records the level of attention among 18 students during an interactive and lecture portion of a single class. If she computes a related samples test at a 0.05 level of significance (two-tailed test), then what is the critical value for this test?

±1.734

±1.740

±2.110

±2.101

12. A researcher computes the mean difference in locomotion in a sample of 12 rats before and 30 minutes after an injection of amphetamine. Rats were placed in a box with infrared beams. The number of times rats crossed the beams was used as a measure of locomotion. The mean difference in locomotion was 6.2 ± 8.4 (MD ± SD), and this difference was significant. What is the effect size for this result using estimated Cohen’s d?

d = 0.74 (medium effect)

d = 1.36 (medium effect)

d = 0.74 (large effect)

d = 1.36 (large effect)

13. A researcher reports with 90% confidence that 31% to 37% of Americans believe in ghosts. What is the point estimate for this interval?

31%

34%

37%

31% to 37%

14. In a sample of 20 participants, a researcher estimates the 95% CI for a sample with a mean of M = 5.4 and an estimated standard error (SM) of 1.6. What is the upper confidence limit for this interval?

2.1

3.8

7.0

8.8

15. There is no difference between a point estimate and an interval estimate.

True

False

16. Using a between-subjects ANOVA design,

n · k participants are each observed one time

n participants are observed k times

data are not analyzed between groups

the same participants are observed in each group

17. A researcher measures attractiveness ratings of a male confederate among 30 women who were told the confederate was either single, dating, or married (n = 10 per group). What are the degrees of freedom for error for the one-way between-subjects ANOVA?

2

3

27

28

18. A researcher measures differences in romantic feelings among adolescent and adult males. If different participants were in each group, then what type of statistical design is appropriate for this study?

a two-independent sample t test

a one-way between-subjects ANOVA

a two-way between-subjects ANOVA

both a two-independent sample t test and a one-way between-subjects ANOVA

19. Which of the following post hoc tests is associated with the greatest power to detect an effect?

Schaffé test

Tukey’s HSD test

Bonferroni test

Fisher’s LSD test

20. A researcher computes a one-way within-subjects ANOVA in which k = 4 and n = 20.

What are the degrees of freedom error for this test?

57

79

80

There is not enough information to answer this question.

21. A researcher computes the following one-way within-subjects ANOVA table for a study in which k = 3 and n = 12.

State the decision at a 0.05 level of significance.

 Source of Variation SS df MS Fobt Between groups 450 Between persons 20 Within groups (error) Total 1030

Reject the null hypothesis.

Retain the null hypothesis.

There is not enough information to answer this question.

22. There are ____ factors in a 2 × 3 ANOVA design.

2

3

5

6

23. A researcher conducts a 2 × 4 between-subjects ANOVA in which 12 participants were observed in each group. If SSB = 18 and SSE = 264 for this study, then what is the decision for Factor B at a 0.05 level of significance?

Reject the null hypothesis.

Retain the null hypothesis.

There is not enough information to answer this question.

24. A statistical procedure used to describe the strength and direction of the linear relationship between two factors is called

effect size

power

a correlation

coincidence

25. A researcher measures the following correlation: r = −0.21. What is the value of the coefficient of determination?

0.04

−0.04

0.42

−0.42

26. A researcher measures the correlation between the frequency of self-esteem (high, low) and health status (lean/healthy, overweight/obese). Based on the frequencies for each nominal category given below, what is the value of the phi correlation coefficient?

 Health Status Overweight/Obese Lean/Healthy Self-Esteem Low 32 18 High 18 32

0.08

0.28

0.52

0.56

27. Linear regression describes the extent to which _______ predicts ________.

X; Y

the predictor variable; the criterion variable

the known variable; the to-be-predicted variable

all of the above

28. A researcher reports the following equation for a best-fitting straight line to a set of data points: = −1.01X + 3.24.Which value is the y-intercept? X

ñ1.01

3.24

29. If the coefficient of determination is 0.12 and SSY = 225, then what is the sum of squares regression for an analysis of regression?

27

198

225

There is not enough information to answer this question.

30. A chi-square goodness-of-fit test shows that the frequencies observed fit well with those that were expected. Hence, the decision was to

reject the null hypothesis

retain the null hypothesis

31. A researcher asks participants to taste each of three meals and to choose the one they like best. The same foods are in each meal, however the calorie total of each meal is different. One is low in calories, one is moderate in calories and one is high in calories. Based on the observed frequencies given below, what is an appropriate conclusion for this test at a .05 level of significance?

 Type of Meal Low Calorie Moderate Calorie High Calorie fo 6 7 17 fe 10 10 10

Participants liked the high calorie meal more than the low calorie meal.

Participants liked the low calorie meal less than the moderate calorie meal.

Participants liked the high calorie meal more than was expected.

all of the above

32. Each of the following is an appropriate test for ordinal data, except

the Mann-Whitney U test

the chi-square goodness-of-fit test

the one-sample sign test

the Friedman test

33. A professor ranks the grades of students in each of three sections of a statistics course. He computes H = 6.83 for the Kruskal-Wallis H test to test for differences between the sections. What is the decision for this test?

Retain the null hypothesis.

Reject the null hypothesis.

There is not enough information to answer this question.

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