Question 1

Given the information:   the number of degrees of freedom that should be used in the pooled variance t -test is:

Accepted Answer

A) 40 
B) 38 
C) 15 
D) 25 
A) 40 
B) 38 
C) 15 
D) 25

Question 2

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

Accepted Answer

A) sample sizes are equal. 
B) populations are normal. 
C) means are equal. 
D) All of these choices are true. 
A) sample sizes are equal. 
B) populations are normal. 
C) means are equal. 
D) All of these choices are true.

Question 3

In comparing the difference in means with a matched pairs experiment, the variable under consideration is   , where the subscript D refers to the difference.

Accepted Answer

A) True 
 B)False

Question 4

The expected value of the difference of two sample means equals the difference of the corresponding population means when:

Accepted Answer

A) the populations are normally distributed. 
B) the samples are independent. 
C) the populations are approximately normal and the sample sizes are large. 
D) All of these choices are true. 
A) the populations are normally distributed. 
B) the samples are independent. 
C) the populations are approximately normal and the sample sizes are large. 
D) All of these choices are true.

Question 5

When the sample sizes are equal, the pooled variance of the two samples is the average of the two sample variances.

Accepted Answer

A) True 
 B)False

Question 6

The unequal-variances test statistic of   has an approximate ____________________ distribution with n 1 + n 2 - 2 degrees of freedom.

Accepted Answer

Question 7

The pooled variance estimator is the ____________________ average of the two sample variances.

Accepted Answer

The answer of The pooled variance estimator is the ____________________...

Question 8

Clothing Expenditures A marketing consultant was in the process of studying the perceptions of married couples concerning their monthly clothing expenditures. He believed that the husband's perception would be higher than the wife's. To judge his belief, he takes a random sample of ten married couples and asks each spouse to estimate the family clothing expenditure (in dollars)during the previous month. The data are shown below.   {Clothing Expenditures Narrative} Estimate with 95% confidence the population mean difference.

Accepted Answer

32 ± 26.076. Thus, L

Question 9

When testing   vs.   , the observed value of the z -score was found to be - 2.15. Then, the p -value for this test would be

Accepted Answer

A) .0158 
B) .0316 
C) .9842 
D) .9684 
A) .0158 
B) .0316 
C) .9842 
D) .9684

Question 10

Two measurements from the same individuals is an example of data collected from a matched pairs experiment.

Accepted Answer

A) True 
 B)False

Question 11

The pooled-variances t -test requires that the two population variances need not be the same.

Accepted Answer

A) True 
 B)False

Question 12

Two independent samples of sizes 20 and 30 are randomly selected from two normally distributed populations. Assume that the population variances are unknown but equal. In order to test the difference between the population means,   , the sampling distribution of the sample mean difference,   , is:

Accepted Answer

A) normal. 
B) Student -t with 50 degrees of freedom. 
C) Student -t with 48 degrees of freedom. 
D) None of these choices. 
A) normal. 
B) Student -t with 50 degrees of freedom. 
C) Student -t with 48 degrees of freedom. 
D) None of these choices.

Question 13

Two independent samples of sizes 40 and 50 are randomly selected from two populations to test the difference between the population means   . Assume the population variances are known. The sampling distribution of the sample mean difference   is:

Accepted Answer

A) normally distributed. 
B) approximately normal. 
C) Student t- distributed with 88 degrees of freedom. 
D) None of these choices. 
A) normally distributed. 
B) approximately normal. 
C) Student t- distributed with 88 degrees of freedom. 
D) None of these choices.

Question 14

The equal-variances test statistic of   is Student t -distributed with n 1 + n 2 degrees of freedom, provided that the two populations are normal.

Accepted Answer

A) True 
 B)False

Question 15

Undergraduates' Test Scores 35 undergraduate students who completed two years of college were asked to take a basic mathematics test. The mean and standard deviation of their scores were 75.1 and 12.8, respectively. In a random sample of 50 students who only completed high school, the mean and standard deviation of the test scores were 72.1 and 14.6, respectively {Undergraduates' Test Scores Narrative} Can we infer at the 10% significance level that a difference exists between the two groups?

Accepted Answer

@#IMG-DLM& , @#IMG-DLM& Rejection region: | t | > t _0.05,83 » 1.664

Question 16

In testing for differences between the means of two independent populations the null hypothesis is:

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 17

Promotional Campaigns The general manager of a chain of fast food chicken restaurants wants to determine how effective their promotional campaigns are. In these campaigns "20% off" coupons are widely distributed. These coupons are only valid for one week. To examine their effectiveness, the executive records the daily gross sales (in $1,000s)in one restaurant during the campaign and during the week after the campaign ends. The data is shown below. 
 Day Sales During Campaign Sales After Campaign   {Promotional Campaigns Narrative} Estimate with 95% confidence the mean difference and interpret.

Accepted Answer

0.957 ± 0.57. Thus, LCL = 0.38

Question 18

Clothing Expenditures A marketing consultant was in the process of studying the perceptions of married couples concerning their monthly clothing expenditures. He believed that the husband's perception would be higher than the wife's. To judge his belief, he takes a random sample of ten married couples and asks each spouse to estimate the family clothing expenditure (in dollars)during the previous month. The data are shown below.   {Clothing Expenditures Narrative} Can the consultant conclude at the 5% significance level that the husband's estimate is higher than the wife's estimate?

Accepted Answer

@#IMG-DLM& , @#IMG-DLM& (husband - wife)Rejection region: t

Question 19

A political analyst in Hawaii surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans. This would be an example of:

Accepted Answer

A) independent samples. 
B) dependent samples. 
C) independent samples only if the sample sizes are equal. 
D) dependent samples only if the sample sizes are equal. 
A) independent samples. 
B) dependent samples. 
C) independent samples only if the sample sizes are equal. 
D) dependent samples only if the sample sizes are equal.

Question 20

A test is being conducted to test the difference between two population means using data that are gathered from a matched pairs experiment. If the paired differences are normal, then the distribution used for testing is the:

Accepted Answer

A) normal distribution. 
B) binomial distribution. 
C) Student t -distribution. 
D) F -distribution. 
A) normal distribution. 
B) binomial distribution. 
C) Student t -distribution. 
D) F -distribution.

Given the information: the number of degrees of freedom that should be used in the pooled variance t -test is:

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

In comparing the difference in means with a matched pairs experiment, the variable under consideration is , where the subscript D refers to the difference.

The expected value of the difference of two sample means equals the difference of the corresponding population means when:

When the sample sizes are equal, the pooled variance of the two samples is the average of the two sample variances.

The unequal-variances test statistic of has an approximate ____________________ distribution with n ₁ + n ₂ - 2 degrees of freedom.

The pooled variance estimator is the ____________________ average of the two sample variances.

When testing vs. , the observed value of the z -score was found to be - 2.15. Then, the p -value for this test would be

Two measurements from the same individuals is an example of data collected from a matched pairs experiment.

The pooled-variances t -test requires that the two population variances need not be the same.

Two independent samples of sizes 20 and 30 are randomly selected from two normally distributed populations. Assume that the population variances are unknown but equal. In order to test the difference between the population means, , the sampling distribution of the sample mean difference, , is:

Two independent samples of sizes 40 and 50 are randomly selected from two populations to test the difference between the population means . Assume the population variances are known. The sampling distribution of the sample mean difference is:

The equal-variances test statistic of is Student t -distributed with n ₁ + n ₂ degrees of freedom, provided that the two populations are normal.

In testing for differences between the means of two independent populations the null hypothesis is:

A political analyst in Hawaii surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans. This would be an example of:

A test is being conducted to test the difference between two population means using data that are gathered from a matched pairs experiment. If the paired differences are normal, then the distribution used for testing is the:

What Is Statistics

Graphical and Tabular Descriptive Techniques

Numerical Descriptive Techniques

Data Collection and Sampling

Probability

Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Introduction to Estimation

Introduction to Hypothesis Testing

Inference About a Population

Inference About Comparing Two Populat

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlat

Multiple Regression

Review of Statistical Inference

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Exam 12: Inference About Comparing Two Populat

Given the information: the number of degrees of freedom that should be used in the pooled variance t -test is:

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

In comparing the difference in means with a matched pairs experiment, the variable under consideration is , where the subscript D refers to the difference.

The expected value of the difference of two sample means equals the difference of the corresponding population means when:

When the sample sizes are equal, the pooled variance of the two samples is the average of the two sample variances.

The unequal-variances test statistic of has an approximate ____________________ distribution with n 1 + n 2 - 2 degrees of freedom.

The pooled variance estimator is the ____________________ average of the two sample variances.

When testing vs. , the observed value of the z -score was found to be - 2.15. Then, the p -value for this test would be

Two measurements from the same individuals is an example of data collected from a matched pairs experiment.

The pooled-variances t -test requires that the two population variances need not be the same.

Two independent samples of sizes 20 and 30 are randomly selected from two normally distributed populations. Assume that the population variances are unknown but equal. In order to test the difference between the population means, , the sampling distribution of the sample mean difference, , is:

Two independent samples of sizes 40 and 50 are randomly selected from two populations to test the difference between the population means . Assume the population variances are known. The sampling distribution of the sample mean difference is:

The equal-variances test statistic of is Student t -distributed with n 1 + n 2 degrees of freedom, provided that the two populations are normal.

In testing for differences between the means of two independent populations the null hypothesis is:

A political analyst in Hawaii surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans. This would be an example of:

A test is being conducted to test the difference between two population means using data that are gathered from a matched pairs experiment. If the paired differences are normal, then the distribution used for testing is the:

What Is Statistics

Graphical and Tabular Descriptive Techniques

Numerical Descriptive Techniques

Data Collection and Sampling

Probability

Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Introduction to Estimation

Introduction to Hypothesis Testing

Inference About a Population

Inference About Comparing Two Populat

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlat

Multiple Regression

Review of Statistical Inference

Filters

The unequal-variances test statistic of has an approximate ____________________ distribution with n ₁ + n ₂ - 2 degrees of freedom.

The equal-variances test statistic of is Student t -distributed with n ₁ + n ₂ degrees of freedom, provided that the two populations are normal.