Question 1

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences.They randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training.Which statistical analysis should be performed to answer the researchers' question?
A) single-sample t test
B) z test
C) independent-samples t test
D) dependent-samples t test

Accepted Answer

The correct statistical analysis for comparing the means of two independent groups (control group vs. relaxation training group) is the independent-samples t test.

Question 2

The mean of the comparison distribution for the null hypothesis of an independent-samples t test is:
A) always 0.
B) sometimes 0.
C) always 1.
D) sometimes 1.

Accepted Answer

The mean of the comparison distribution for the null hypothesis of an independent-samples t test is always 0 because it represents the hypothesis that there is no difference between the groups, hence a mean difference of 0.

Question 3

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences.They randomly assigned 20 participants to a control group (no relaxation training) or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training.The independent variable in this study is:
A) training type.
B) number of headaches.
C) control group.
D) relaxation training.

Accepted Answer

The independent variable is the variable that is manipulated by the researchers to observe its effect on another variable. In this study, the manipulation is the type of training (relaxation training vs. no training), making "training type" the independent variable.

Question 4

There are three steps involved in creating the comparison distribution for the independent-samples t test, and those steps are repeated many times.Which of these is the sequence described in the text?
A) randomly select a pair of scores, subtract the second score from the first, and record the difference between scores
B) randomly select a group of scores, calculate their mean, and plot that mean on a distribution
C) randomly select scores and calculate their mean as the group 1 mean, randomly select another group of scores and calculate their mean as the group 2 mean, and subtract the second mean from the first
D) randomly select a score, subtract the mean from the score, and plot the difference

Accepted Answer

The three steps involved in creating the comparison distribution for the independent-samples t test are (1) randomly selecting scores and calculating their mean as the group 1 mean, (2) randomly selecting another group of scores and calculating their mean as the group 2 mean, and (3) subtracting the group 2 mean from the group 1 mean to obtain a difference score. This process is repeated many times to create a distribution of difference scores, which is then used to calculate the probability of obtaining the observed difference between the sample means by chance alone. Option A describes the process for creating a distribution for a single sample, not for the independent-samples t test. Option B describes the process for creating a distribution of sample means for one group, not for the independent-samples t test. Option D describes the process for creating a distribution of individual scores around the mean for a single sample, not for the independent-samples t test.

Question 5

Mehl (2007) published in the journal Science the results of an extensive study of 396 men and women comparing the number of words uttered per day by each sex.Which statistical test should Mehl use to analyze the data?
A) single-sample t test
B) z test
C) independent-samples t test
D) dependent-samples t test

Accepted Answer

Mehl should use an independent-samples t test since she is comparing the number of words uttered per day between two different groups (men and women) and the sample sizes for each group are different (396 men and women).

Question 6

In a(n) _____, each participant is assigned to only one group in order to compare mean differences in a between-groups design.
A) single-sample t test
B) z test
C) independent-samples t test
D) dependent-samples t test

Accepted Answer

The independent-samples t test is a between-groups design that compares mean differences between two groups. Each participant is only assigned to one group, making it different from a dependent-samples t test where each participant is assigned to both groups. The single-sample t test and z test are both used for within-group designs.

Question 7

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences.They randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training.The dependent variable in this study is:
A) training type.
B) number of headaches.
C) control group.
D) relaxation training.

Accepted Answer

The number of headaches is the variable being measured and compared between the two groups, making it the dependent variable in the study. The other options (training type, control group, relaxation training) are independent variables or groupings within the study.

Question 8

In a(n) _____, each participant is assigned to only one group in order to compare mean differences.
A) single-sample t test
B) z test
C) independent-samples t test
D) dependent-samples t test

Accepted Answer

The independent-samples t test is used when each participant is assigned to only one of two groups in order to compare mean differences between the groups. The other options are not appropriate for this scenario.

Question 9

Dr.Jameson wanted to know if IQ scores differed between male and female participants in his study.He gave 28 participants an IQ test and then compared IQ scores for gender differences.He hypothesized that there would be a statistically significant gender difference in IQ scores.Contrary to Dr.Jameson's hypothesis, there were no differences in IQ scores between men and women in his study.What is the independent variable in this study?
A) IQ scores
B) sample size of 28
C) gender
D) participants

Accepted Answer

The independent variable is the variable that is being manipulated or changed in the study. In this case, the independent variable is gender, as Dr. Jameson is comparing IQ scores between male and female participants.

Question 10

The comparison distribution for an independent-samples t test is a distribution of:
A) differences between means.
B) means.
C) mean of difference of scores.
D) scores.

Accepted Answer

The comparison distribution for an independent-samples t test is a distribution of differences between means. It is used to compare the means of two separate and independent groups or conditions to determine whether there is a significant difference between them.

Question 11

Checking an independent-samples t test for the assumption of normality is part of step _____ of the six steps.
A) 1
B) 2
C) 3
D) 4

Accepted Answer

The answer of Checking an independent-samples t test for the...

Question 12

The appropriate hypothesis test to use for a between-groups design with two groups is a(n):
A) z test.
B) paired-samples t test.
C) independent-samples t test.
D) single-sample t test.

Accepted Answer

The appropriate hypothesis test to use for a between-groups design with two groups is an independent-samples t test. This test is used to determine if there is a statistically significant difference between the means of two independent groups. Option A, z test, is not appropriate for small sample sizes. Option B, paired-samples t test, is used for within-group designs where the same individuals are measured twice. Option D, single-sample t test, is used when comparing a sample mean to a known population mean.

Question 13

Unnithan, Houser, and Fernhall (2006) were interested in whether playing the game Dance Dance Revolution (DDR) affected the heart rate of overweight and non-overweight adolescents differently.A group of 22 adolescents, 10 classified as overweight and 12 as not overweight played DDR for 12 minutes, during which time the researchers measured each participant's heart rate.Which statistical test should the researchers use to analyze their data?
A) single-sample t test
B) z test
C) independent-samples t test
D) dependent-samples t test

Accepted Answer

The researchers are comparing two independent groups (overweight and non-overweight), so an independent-samples t test is the most appropriate statistical test for this study.

Question 14

Dr.Jameson wanted to know if IQ scores differed between male and female participants in his study.He gave 28 participants an IQ test and then compared IQ scores for gender differences.He hypothesized that there would be a statistically significant gender difference in IQ scores.Contrary to Dr.Jameson's hypothesis, there were no differences in IQ scores between men and women in his study.Based on the information provided, does this study meet the assumption of normality? Why or why not?
A) Yes; it is normally distributed because the sample size is large.
B) No; it is not normally distributed because the small sample size is small.
C) We do not know whether it is normally distributed, and the sample size is not at least 30 participants.
D) Yes; the population is likely to be normally distributed because the sample size is less than 30.

Accepted Answer

We do not know whether the IQ scores are normally distributed because the normality assumption requires a sample size of at least 30 participants, and the sample size in this study is only 28. Therefore, we cannot make assumptions about the shape of the distribution of IQ scores in the population.

Question 15

A clinical researcher was interested in determining whether her interventions for depression were effective in minimizing depression symptoms among her participants.To assess the effectiveness of her treatment program, she administered a depression inventory prior to treatment and after treatment.She hypothesized that depression scores would be lower at time two compared to time one.She then compared the mean differences between the two groups and found that her treatment was effective.Which statistical test was the researcher MOST likely to have used to test her hypothesis?
A) single-sample t test
B) z test
C) independent-samples t test
D) paired-samples t test

Accepted Answer

The researcher administered the depression inventory to the same group of participants twice, before and after the treatment, so the appropriate statistical test is the paired-samples t test, which compares the means of two related groups. The single-sample t test is used to compare the mean of one group to a known or hypothesized value. The z test is used when the population standard deviation is known. The independent-samples t test is used to compare the means of two independent groups.

Question 16

Dr.Jameson wanted to know if IQ scores differed between male and female participants in his study.He gave 28 participants an IQ test and then compared IQ scores for gender differences.He hypothesized that there would be a statistically significant gender difference in IQ scores.Contrary to Dr.Jameson's hypothesis, there were no differences in IQ scores between men and women in his study.Which test was Dr.Jameson MOST likely to use to test his hypothesis?
A) paired-samples t test
B) z test
C) independent-samples t test
D) single-samples t test

Accepted Answer

The independent-samples t test is used to compare means between two independent groups. In this case, the two groups are males and females, who are independent of each other. The paired-samples t test is used to compare means within the same group before and after treatment or under different conditions. The z test is used when the population mean and standard deviation are known. The single-samples t test is used to compare the mean of a single sample to a known population mean. None of these tests are applicable to Dr.Jameson's study. Therefore, the most appropriate option is the independent-samples t test.

Question 17

In a(n) _____, a within-groups design with two groups is used to compare the distribution of mean difference scores.
A) single-sample t test
B) z test
C) independent-samples t test
D) paired-samples t test

Accepted Answer

The question mentions a within-groups design with two groups, which indicates that paired-samples t test is the appropriate choice. The other options involve different designs or number of groups.

Question 18

A psychologist is interested in whether working memory is influenced by sleep loss.The psychologist administers a measure of working memory to two groups of subjects.The subjects in one group were kept awake for the entire night and the subjects in the other group maintained their normal sleep schedules.Which statistical analysis should be performed to answer the question "Does sleep loss affect working memory?"
A) single-sample t test
B) z test
C) independent-samples t test
D) paired-samples t test

Accepted Answer

The researcher is comparing two independent groups (those who were kept awake and those who maintained normal sleep schedules), so the appropriate statistical analysis is the independent-samples t test.

Question 19

In a(n) _____, one sample is used to compare a distribution of means during hypothesis testing.
A) single-sample t test
B) z test
C) independent-samples t test
D) dependent-samples t test

Accepted Answer

A single-sample t test is used when there is only one sample available to compare to the population mean during hypothesis testing. The other options (B, C, and D) involve comparing means between two or more samples.

Question 20

Dr.Jameson wanted to know if IQ scores differed between male and female participants in his study.He gave 28 participants an IQ test and then compared IQ scores for gender differences.He hypothesized that there would be a statistically significant gender difference in IQ scores.Contrary to Dr.Jameson's hypothesis, there were no differences in IQ scores between men and women in his study.What is the dependent variable in this study?
A) IQ scores
B) sample size of 28
C) gender
D) participants

Accepted Answer

The dependent variable is the variable being measured and compared between groups, which is the IQ scores in this study.

Quiz 11: The Independent-Samples T Test

The mean of the comparison distribution for the null hypothesis of an independent-samples t test is:

There are three steps involved in creating the comparison distribution for the independent-samples t test, and those steps are repeated many times.Which of these is the sequence described in the text?

Mehl (2007) published in the journal Science the results of an extensive study of 396 men and women comparing the number of words uttered per day by each sex.Which statistical test should Mehl use to analyze the data?

In a(n) _____, each participant is assigned to only one group in order to compare mean differences in a between-groups design.

In a(n) _____, each participant is assigned to only one group in order to compare mean differences.

The comparison distribution for an independent-samples t test is a distribution of:

Checking an independent-samples t test for the assumption of normality is part of step _____ of the six steps.

The appropriate hypothesis test to use for a between-groups design with two groups is a(n) :

In a(n) _____, a within-groups design with two groups is used to compare the distribution of mean difference scores.

In a(n) _____, one sample is used to compare a distribution of means during hypothesis testing.