Question 1

When figuring the pooled population variance estimate in a t test for independent means,

Accepted Answer

A) the variance of at least one of the original populations must be known,as opposed to estimated,but the other can be estimated from sample scores. 
B) the variance of BOTH of the original populations must be known,as opposed to estimated. 
C) the estimates based on each of the samples are averaged in such a way as to give more influence to the estimate based on more participants. 
D) the scores from both samples are combined to form a single sample,and the estimated variance is figured in the usual way using this combined sample. 
A) the variance of at least one of the original populations must be known,as opposed to estimated,but the other can be estimated from sample scores. 
B) the variance of BOTH of the original populations must be known,as opposed to estimated. 
C) the estimates based on each of the samples are averaged in such a way as to give more influence to the estimate based on more participants. 
D) the scores from both samples are combined to form a single sample,and the estimated variance is figured in the usual way using this combined sample. C

Question 2

The comparison distribution for a t test for independent means is a

Accepted Answer

A) distribution of differences between means. 
B) Z distribution (that is,a normal curve). 
C) poisson distribution. 
D) distribution of proportional variance scores. 
A) distribution of differences between means. 
B) Z distribution (that is,a normal curve). 
C) poisson distribution. 
D) distribution of proportional variance scores. A

Question 3

In the formula,t = (M1 - M2)/ Sdifference,"Sdifference" is

Accepted Answer

A) the sum of the standard deviations of the distribution of means. 
B) the pooled estimate of the populations' standard deviation. 
C) the standard deviation of the distribution of differences between means. 
D) the average standard deviation of the two samples. 
A) the sum of the standard deviations of the distribution of means. 
B) the pooled estimate of the populations' standard deviation. 
C) the standard deviation of the distribution of differences between means. 
D) the average standard deviation of the two samples. C

Question 4

If 15 participants take a creativity test twice,once in a normal mental state and once under the influence of an experimental drug,the appropriate test to analyze the data is a t test for __________.

Accepted Answer

The answer of If 15 participants take a creativity test...

Question 5

A health psychologist conducted an experiment in which participants watched a film that either did or did not include a person being injured because of not wearing a seat belt.A week later,as part of a seemingly different study,these same participants reported how important they thought it was to wear seat belts.The 22 participants who had seen the injury film gave a mean rating of 8.3,with an estimated population standard deviation of 1.6.The 30 participants in the control condition had a mean of 7.4 with an estimated population standard deviation of 2.2.Using the .01 significance level,does seeing a movie where a person gets injured due to not wearing a seat belt make attitudes more positive towards seat belt usage as indicated by higher ratings?
a.Use the five steps of hypothesis testing.
b.Sketch the distributions involved.
c.Figure the effect size.
d.Explain the logic of what you did to a person who is familiar with the t test for a single sample,but who is unfamiliar with the t test for independent means.Be sure you explain how this problem differs from a t test for a single sample.Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and the logic of all the steps of figuring you did to determine those characteristics.

Accepted Answer

A) @#IMG-DLM& Do not reject the null hyp

Question 6

A social psychologist interested in cultural differences compared women of two ethnic groups on a Role Approval Index on which high scores indicated high degrees of approval of one's own social role. The results were as follows.  
-What is the pooled estimate of the population variance?

Accepted Answer

A) [(14 / 36)(6.5)] + [(22 / 36)(4.5)] = 5.28 
B) [(15 / 38)(6.5)] + [(23 / 38)(4.5)] = 5.29 
C) [(15 / 23)(6.5)] + [(23 / 15)(4.5)] = 11.14 
D) [(14 / 22)(6.5)] + [(22 / 14)(4.5)] = 11.21 
A) [(14 / 36)(6.5)] + [(22 / 36)(4.5)] = 5.28 
B) [(15 / 38)(6.5)] + [(23 / 38)(4.5)] = 5.29 
C) [(15 / 23)(6.5)] + [(23 / 15)(4.5)] = 11.14 
D) [(14 / 22)(6.5)] + [(22 / 14)(4.5)] = 11.21

Question 7

Advanced topic: If a study has 18 participants in the experimental group and 7 in the control group,what is the harmonic mean?

Accepted Answer

A) 18/(18+7)+ 7/(18+7)= 1.00 
B) (2)(18)/(18+7)+ (2)(7)/(18+7)= 2.00 
C) (2)(18)(7)/ (18+7)= 10.08 
D) (18+7)2 / (18+7)= 25 
A) 18/(18+7)+ 7/(18+7)= 1.00 
B) (2)(18)/(18+7)+ (2)(7)/(18+7)= 2.00 
C) (2)(18)(7)/ (18+7)= 10.08 
D) (18+7)2 / (18+7)= 25

Question 8

In which of the following situations would a t test for independent means be conducted?

Accepted Answer

A) a comparison of the SAT scores of a group of 10 students who completed a special SAT preparation course compared to the scores of students in general on the SAT 
B) a comparison of scores of participants in a memory study where one group is assigned to learn the words in alphabetical order and another group is assigned to learn the words in order of length of the word 
C) a comparison of participants' scores on a skills test before and after attending a training session intended to improve the skill 
D) a comparison of participants' logical reasoning skills with the general population 
A) a comparison of the SAT scores of a group of 10 students who completed a special SAT preparation course compared to the scores of students in general on the SAT 
B) a comparison of scores of participants in a memory study where one group is assigned to learn the words in alphabetical order and another group is assigned to learn the words in order of length of the word 
C) a comparison of participants' scores on a skills test before and after attending a training session intended to improve the skill 
D) a comparison of participants' logical reasoning skills with the general population

Question 9

The symbol "S2M2" represents __________.

Accepted Answer

the variance of the

Question 10

Advanced topic: The value of the harmonic mean

Accepted Answer

A) is disproportionately influenced by smaller numbers (meaning,smaller sample sizes). 
B) is disproportionately influenced by larger numbers (meaning,larger sample sizes). 
C) is equidistant from both group sizes. 
D) cannot be determined without more information. 
A) is disproportionately influenced by smaller numbers (meaning,smaller sample sizes). 
B) is disproportionately influenced by larger numbers (meaning,larger sample sizes). 
C) is equidistant from both group sizes. 
D) cannot be determined without more information.

Question 11

In an experiment with 48 participants,a small effect size is most likely to be detected if the experimenter assigns __________ participants to the experimental group and __________ participants to the control group.(Give numbers.)

Accepted Answer

The answer of In an experiment with 48 participants,a small...

Question 12

One of the assumptions for the t test for independent means is that

Accepted Answer

A) sample means are not significantly different. 
B) the mean of the distribution of differences between means is 1. 
C) the variance of each of the parent populations is the same. 
D) the mean of each of the parent populations vary by no more than 1 standard deviation. 
A) sample means are not significantly different. 
B) the mean of the distribution of differences between means is 1. 
C) the variance of each of the parent populations is the same. 
D) the mean of each of the parent populations vary by no more than 1 standard deviation.

Question 13

The computer-based procedures statisticians use to evaluate how well statistical tests like the t test for independent means hold up when their assumptions are violated by making many repeated computations using random numbers are called __________.

Accepted Answer

The answer of The computer-based procedures statisticians use to evaluate...

Question 14

Assuming the null hypothesis is true in each case,if the results of 100 studies are analyzed,each using the .01 significance level,on average __________ will be significant.(Give a number.)

Accepted Answer

The answer of Assuming the null hypothesis is true in...

Question 15

A forensic psychologist conducted a study to examine whether being hypnotized during recall affects how well a witness can remember facts about an event.Nine participants watched a short film of a mock robbery,after which each participant was questioned about what he or she had seen.The five participants in the experimental group were questioned while they were hypnotized and gave 14,18,13,20,and 10 accurate responses.The four participants in the control group gave 16,20,17,and 19 accurate responses.Using the .05 significance level,do hypnotized witnesses perform differently than witnesses who are not hypnotized?
a.Use the five steps of hypothesis testing.
b.Sketch the distributions involved.
c.Figure the effect size.
d.Explain the logic of what you did to a person who is familiar with the t test for a single sample,but who is unfamiliar with the t test for independent means.Be sure you explain how this problem differs from a t test for a single sample.Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and the logic of all the steps of figuring you did to determine those characteristics.

Accepted Answer

A) @#IMG-DLM& Do not reject the null hyp

Question 16

The results of a t test for independent means can be misleading when the sample variances are

Accepted Answer

A) not at all different (e.g.,a 1 : 1 ratio). 
B) a little different (e.g.,a 1.5 : 1 ratio). 
C) moderately different (e.g.,a 2 : 1 ratio). 
D) very different (e.g.,a 4 : 1 ratio). 
A) not at all different (e.g.,a 1 : 1 ratio). 
B) a little different (e.g.,a 1.5 : 1 ratio). 
C) moderately different (e.g.,a 2 : 1 ratio). 
D) very different (e.g.,a 4 : 1 ratio).

Question 17

A theater arts department enlisted the help of a social psychology professor to design a study to see if being surrounded by highly attractive people affected the performance of young actors.Thirty student actors were randomly assigned to act a particular scene under one of two conditions: For 13 of the actors,the other performers were dressed and made up to look very attractive; for the other 17 actors,the other performers were dressed and made up to look very unattractive.A panel of judges rated the performance of the two groups,and the mean performance ratings for the actors with attractive co-performers was 4.3 (S = .86)and with unattractive co-performers,the mean was 5.4 (S = 1.30).Using the .05 significance level,did acting with attractive co-performers affect performance?
a.Use the five steps of hypothesis testing.
b.Sketch the distributions involved.
c.Figure the effect size.
d.Explain the logic of what you did to a person who is familiar with the t test for a single sample,but who is unfamiliar with the t test for independent means.Be sure you explain how this problem differs from a t test for a single sample.Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and the logic of all the steps of figuring you did to determine those characteristics.

Accepted Answer

A) @#IMG-DLM& Reject the null hypothesis

Question 18

Assuming that the difference between two independent sample means is 6.24,and S2difference = 27,the calculated t score should be __________.

Accepted Answer

Question 19

Even if the population variances are somewhat different,the t test for independent means would probably still be accurate because this test is __________ to violations of the assumption of equal population variances.

Accepted Answer

The answer of Even if the population variances are somewhat...

Question 20

Which statement is only true for the t test for dependent means rather than t tests in general?

Accepted Answer

A) Population variances are estimated from the information in the sample of scores actually studied. 
B) Pretest-posttest experimental designs are common. 
C) The population means are unknown. 
D) The sample scores (in some form)are compared to a t distribution. 
A) Population variances are estimated from the information in the sample of scores actually studied. 
B) Pretest-posttest experimental designs are common. 
C) The population means are unknown. 
D) The sample scores (in some form)are compared to a t distribution.

When figuring the pooled population variance estimate in a t test for independent means,

The comparison distribution for a t test for independent means is a

In the formula,t = (M₁ - M₂)/ S_difference,"S_difference" is

If 15 participants take a creativity test twice,once in a normal mental state and once under the influence of an experimental drug,the appropriate test to analyze the data is a t test for __________.

A social psychologist interested in cultural differences compared women of two ethnic groups on a Role Approval Index on which high scores indicated high degrees of approval of one's own social role. The results were as follows. -What is the pooled estimate of the population variance?

Advanced topic: If a study has 18 participants in the experimental group and 7 in the control group,what is the harmonic mean?

In which of the following situations would a t test for independent means be conducted?

The symbol "S²_M2" represents __________.

Advanced topic: The value of the harmonic mean

In an experiment with 48 participants,a small effect size is most likely to be detected if the experimenter assigns participants to the experimental group and participants to the control group.(Give numbers.)

One of the assumptions for the t test for independent means is that

The computer-based procedures statisticians use to evaluate how well statistical tests like the t test for independent means hold up when their assumptions are violated by making many repeated computations using random numbers are called __________.

Assuming the null hypothesis is true in each case,if the results of 100 studies are analyzed,each using the .01 significance level,on average __________ will be significant.(Give a number.)

The results of a t test for independent means can be misleading when the sample variances are

Assuming that the difference between two independent sample means is 6.24,and S²_difference = 27,the calculated t score should be __________.

Even if the population variances are somewhat different,the t test for independent means would probably still be accurate because this test is __________ to violations of the assumption of equal population variances.

Which statement is only true for the t test for dependent means rather than t tests in general?

Displaying the Order in a Group of Numbers

Central Tendency and Variability

Some Key Ingredients for Inferential Statistics: Z Scores,the Normal Curve, Sample Versus Population, and Probability

Introduction to Hypothesis Testing

Hypothesis Tests With Means of Samples

Making Sense of Statistical Significance:decision Errors, Effect Size, and Statistical Power

Introduction to T Tests: Single Sample and Dependent Means

Introduction to the Analysis of Variance

Factorial Analysis of Variance

Correlation

Prediction

Chi-Square Tests

Strategies When Population Distributions Are Not Normal: Data Transformations and Rank-Order Tests

The General Linear Model and Making Sense of Advanced Statistical Procedures in Research Articles

Filters

Exam 8: The T Test for Independent Means

When figuring the pooled population variance estimate in a t test for independent means,

The comparison distribution for a t test for independent means is a

In the formula,t = (M1 - M2)/ Sdifference,"Sdifference" is

If 15 participants take a creativity test twice,once in a normal mental state and once under the influence of an experimental drug,the appropriate test to analyze the data is a t test for __________.

A social psychologist interested in cultural differences compared women of two ethnic groups on a Role Approval Index on which high scores indicated high degrees of approval of one's own social role. The results were as follows. -What is the pooled estimate of the population variance?

Advanced topic: If a study has 18 participants in the experimental group and 7 in the control group,what is the harmonic mean?

In which of the following situations would a t test for independent means be conducted?

The symbol "S2M2" represents __________.

Advanced topic: The value of the harmonic mean

In an experiment with 48 participants,a small effect size is most likely to be detected if the experimenter assigns __________ participants to the experimental group and __________ participants to the control group.(Give numbers.)

One of the assumptions for the t test for independent means is that

The computer-based procedures statisticians use to evaluate how well statistical tests like the t test for independent means hold up when their assumptions are violated by making many repeated computations using random numbers are called __________.

Assuming the null hypothesis is true in each case,if the results of 100 studies are analyzed,each using the .01 significance level,on average __________ will be significant.(Give a number.)

The results of a t test for independent means can be misleading when the sample variances are

Assuming that the difference between two independent sample means is 6.24,and S2difference = 27,the calculated t score should be __________.

Even if the population variances are somewhat different,the t test for independent means would probably still be accurate because this test is __________ to violations of the assumption of equal population variances.

Which statement is only true for the t test for dependent means rather than t tests in general?

Displaying the Order in a Group of Numbers

Central Tendency and Variability

Some Key Ingredients for Inferential Statistics: Z Scores,the Normal Curve, Sample Versus Population, and Probability

Introduction to Hypothesis Testing

Hypothesis Tests With Means of Samples

Making Sense of Statistical Significance:decision Errors, Effect Size, and Statistical Power

Introduction to T Tests: Single Sample and Dependent Means

Introduction to the Analysis of Variance

Factorial Analysis of Variance

Correlation

Prediction

Chi-Square Tests

Strategies When Population Distributions Are Not Normal: Data Transformations and Rank-Order Tests

The General Linear Model and Making Sense of Advanced Statistical Procedures in Research Articles

Filters

In the formula,t = (M₁ - M₂)/ S_difference,"S_difference" is

The symbol "S²_M2" represents __________.

In an experiment with 48 participants,a small effect size is most likely to be detected if the experimenter assigns participants to the experimental group and participants to the control group.(Give numbers.)

Assuming that the difference between two independent sample means is 6.24,and S²_difference = 27,the calculated t score should be __________.