The t test for the difference between the means of two independent populations assumes that the respective

a. samples sizes are equal

b. sample medians are equal

c. populations are approximately normal

d. all of the above

Question 3

A researcher is curious about the effect of sleep on students’ test performances. He chooses 100 students and gives each two exams. One exam is given after 4 hours of sleep and one after 8 hours of sleep. The statistical test the researcher should use is the

a. z test for population differences

b. single sample t test

c. independent samples t test

d. paired samples t test

Question 4

A statistics professor wants to know whether grades on a statistics test were the same for the morning and afternoon sections of her classes. For this situation the professor should choose

a. factorial analysis

b. correlation

c. independent samples t test

d. dependent samples t test

Question 5

The sample size for the groups in an independent samples t test must be the same.

a. true

b. false

Question 6

In testing a hypothesis about the difference between two groups, the p value is computed to be 0.043. If the predetermined alpha level was set at 0.05, the null hypothesis should be rejected.

a. true

b. false

Question 9

The F test statistic in a one-way ANOVA is ratio of the

a. sum of squares between to sum of squares total

b. mean squares between groups to mean squares within groups

c. sum of squares between groups to the total degrees of freedom

d. means squares within groups to mean squares total

Question 10

In a one-way ANOVA, the null hypothesis is always

a. all the population means are different

b. some of the population means are different

c. some of the population means are the same

d. all of the population means are the same

Question 11

Fast food chains that offer drive-thru service in the most timely manner are most likely to attract repeat customer visits. A study of 20 drive-thru times at 5 fast-food chains was conducted. The between group degrees of freedom should be

a. 4

b. 5

c. 20

d. 95

e. 100

Question 12

Fast food chains that offer drive-thru service in the most timely manner are most likely to attract repeat customer visits. A study of 20 drive-thru times at 5 fast-food chains was conducted. The research obtains a significant F statistic. The researcher determines that

a. the group with the lowest mean score was the group that was significantly different

b. the groups were all significantly different from each other

c. additional study is needed in order to determine where the significance lies

d. only the group with the highest mean was significantly different

Question 13

The Y intercept of a regression line represents the

a. predicted value of Y when X = 0

b. change in estimated average of Y per unit change in X

c. predicted value of Y

d. variation around the regression line

Question 14

The slope of a regression line represents:

a. predicted value of Y when X = 0

b. change in Y per unit change in X

c. predicted value of Y

d. variation around the regression line

Question 16 (1 point)

The strength of a relationship between two variables is measured by

a. a t test

b. the coefficient of determination

c. Levine’s test of equal variance

d. Post hoc tests

Question 17

Regression analysis is used for prediction, while correlation analysis is used to measure the strength of the association between two numeric variables.

a. true

b. false

Question 18

Which of the following r scores indicates the highest correlation?

a. -0.87

b. 0.75

c. - 0.36

d. 0.48

Question 19

A research study reveals a correlation of r = 0.26. The researcher interprets the statistical significance of this based on which of the following?

a. An r value like this is too low to be significant

b. The r value would have to be less than 0.05 in order to be significant

c. The research needs more information before being able to determine significance

d. Statistical significance is not relevant in correlation analyses

Question 20

An indirect correlation is most likely to be present in which of the following?

a. relationship between height and weight

b. relationship between age and auditory acuity

c. relationship between exercise and endurance

d. relationship between amount of study and course grade

Question 21

21. Which group survived the longest?

a. the chemotherapy group

b. the no chemotherapy group

Question 22

The greatest variance in length of survival occurred in

a. the chemotherapy group

b. the no chemotherapy group

Question 23

There was a significant difference in survival between the two groups.

a. true

b. false

Question 24

The researcher is able to assume equal variance between the two groups.

a. true

b. false

Question 25

25. The highest correlation is found between

a. body weight and binge eating

b. purging and family relations

c. body weight and menstruation

d. binge eating and purging

Question 26

The correlation between mental state (mood) and family relations is

a. low and insignificant

b. medium and significant

c. high and significant

d. low and significant

e. unable to determine based on this print-out

Question 27

Which of the following two variables are indirectly related?

a. body weight and purging

b. body perception and vomiting

c. family relations and vomiting

d. menstruation and mental state (mood)

Question 28

What percent of body perception is related to body weight?

a. 30%

b. 60%

c. 90%

d. 9%

Question 29

a. 5%

b. 22%

c. 38%

d. 43%

Question 30

In the regression equation, the slope would be represented by which of the following numbers?

a. 2.426

b. 5.56

c. -.048 & .385

d. -.031 & .224

Question 31

What kind of correlation is present between age and breast cancer survival time based on data in the following scatterplot?

a. positive correlation

b. negative correlation

c. no correlation

d. unable to determine

Question 32

32. How many groups were analyzed?

a. 1

b. 2

c. 14

d. unknown

Question 33

How many subjects were surveyed?

a. 10

b. 12

c. 13

d. 14

Question 34

There was a significant change in racial attitude

a. true

b. false

Question 35

If the research hypothesis stated that racial attitudes would be significantly more positive after the camp experience, the researcher would document the study outcome by stating a significance level of

a. > .05

b. .002

c. .001

d. >. 001

Question 36

a. true

b. false

c. unable to determine from these tables

Question 37

The mean number of responses for the three groups was the same.

a. true

b. false

c. unable to determine from these tables

Question 38

The null hypothesis can be rejected

a. true

b. false

c. unable to determine from these tables

Question 39

The variance that actually accounts for group differences is

a. between groups

b. within groups

c. total

Question 40

Which of the following is FALSE?

a. normal individuals had significantly more responses than depressed individuals

b. schizophrenic individuals had significantly more responses than depressed individuals

c. depressed individuals had significantly less responses than both normal and schizophrenic individuals

d. normal individuals had significantly more responses than schizophrenic individuals