Exam 13: Inference About Comparing Two Populations

NARRBEGIN: Profit Margin Profit Margin An investor is considering two types of investment. She is quite satisfied that the expected profit margin on Investment 1 is higher than the expected profit margin on Investment 2. However, she is quite concerned that the risk associated with Investment 1 is higher than that of Investment 2. To help make her decision, she randomly selects seven monthly profit margins on investment 1 and ten monthly profit margins on investment 2. She finds that the sample variances of Investments 1 and 2 are 225 and 118, respectively.NARREND -{Profit Margin Narrative} Can she infer at the 5% significance level that the population variance of investment 1 exceeds that of investment 2?

(Essay)

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Question 61

The equal-variances test statistic of $\mu _ { 1 } - \mu _ { 2 }$ is Student t-distributed with n₁ + n₂ -2 degrees of freedom provided that the two populations are ____________________.

(Short Answer)

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Question 62

In a matched pairs experiment the parameter of interest is the of the population of .

(Short Answer)

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Question 63

In testing the difference between the means of two normally distributed populations, the number of degrees of freedom associated with the unequal-variances t-test statistic usually results in a non-integer number. It is recommended that you:

(Multiple Choice)

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Question 64

When testing the equality of two population variances the number in the null hypothesis is 0.

(True/False)

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Question 65

In constructing a confidence interval estimate for the difference between two population proportions, we pool the population proportions when the populations are normally distributed.

(True/False)

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Question 66

The pooled proportion estimate is used when the proportion of successes from sample 1 equals the proportion of successes from sample 2.

(True/False)

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Question 67

In constructing a confidence interval estimate for the difference between two population proportions, we:

(Multiple Choice)

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Question 68

NARRBEGIN: Promotional Campaigns 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 Sunday 18.1 16.6 Monday 10.0 8.8 Tuesday 9.1 8.6 Wednesday 8.4 8.3 Thursday 10.8 10.1 Friday 13.1 12.3 Saturday 20.8 18.9 NARREND -{Promotional Campaigns Narrative} Can they infer at the 5% significance level that sales increase during the campaign?

(Essay)

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Question 69

NARRBEGIN: Headache Medicine Headache Medicine A researcher wants to see if/how men and women differ in their reaction to a headache medicine with respect to drowsiness. In testing the hypotheses $H _ { 0 } : p _ { 1 } - p _ { 2 } = 0.10$ vs. $H _ { 1 } : p _ { 1 } - p _ { 2 } < 0.10$ , the following statistics were obtained: n₁ = 400, x₁ = 208, n₂ = 250, and x₂ = 115, where x₁ and x₂ represent the number of patients in the two samples (men vs. women) who reported to have drowsiness as a result of taking headache medicine.NARREND -{Headache Medicine Narrative} Estimate with 90% confidence the difference between the two population proportions.

(Essay)

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Question 70

The F-distribution is symmetric.

(True/False)

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Question 71

NARRBEGIN: Mass Production Line Mass Production Line A quality control examiner keeps a tally sheet of the number of acceptable and unacceptable products that come off two different production lines. The completed sheet is shown below. Froducts Mass Production Line Acceptable Unacceptable 1 152 48 2 136 54 NARREND -{Mass Production Line Narrative} Estimate with 95% confidence the difference in population proportions.

(Essay)

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Question 72

Both the equal-variances and unequal variances test statistic and confidence interval estimator of $\mu _ { 1 } - \mu _ { 2 }$ require that the two populations be normally distributed.

(True/False)

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Question 73

The pooled proportion estimate is found by taking the proportion of successes from sample 1 plus the proportion of successes from sample 2.

(True/False)

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Question 74

NARRBEGIN: Profit Margin Profit Margin An investor is considering two types of investment. She is quite satisfied that the expected profit margin on Investment 1 is higher than the expected profit margin on Investment 2. However, she is quite concerned that the risk associated with Investment 1 is higher than that of Investment 2. To help make her decision, she randomly selects seven monthly profit margins on investment 1 and ten monthly profit margins on investment 2. She finds that the sample variances of Investments 1 and 2 are 225 and 118, respectively.NARREND -{Profit Margin Narrative} Briefly describe what the interval estimate tells you.

(Essay)

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Question 75

The test statistic employed to test $H _ { 0 } : \sigma _ { 1 } ^ { 2 } / \sigma _ { 2 } ^ { 2 } = 1$ is $F = s _ { 1 } ^ { 2 } / s _ { 2 } ^ { 2 }$ is F-distributed with v₁ = n₁ - 1 and v₂ = n₂ -1 degrees of freedom if the two populations are F-distributed.

(True/False)

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Question 76

In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal, the sampling distribution of the resulting statistic is:

(Multiple Choice)

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Question 77

NARRBEGIN: Worker Safety Worker Safety An OSHA agent wanted to determine if efforts to promote safety have been successful. By checking the records of 250 workers, he found that 30 of them suffered either minor or major injuries that year. A random sample of 400 workers last year revealed that 80 suffered some form of injury.NARREND -{Worker Safety Narrative} What is the p-value of the test? Explain how to use it for testing the hypotheses.

(Essay)

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Question 78

When we test for differences between the means of two independent populations, we can only use a two-tailed test.

(True/False)

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Question 79

The test for the equality of two population variances is based on the:

(Multiple Choice)

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Question 80

Showing 61 - 80 of 168

The equal-variances test statistic of $\mu _ { 1 } - \mu _ { 2 }$ is Student t-distributed with n₁ + n₂ -2 degrees of freedom provided that the two populations are ____________________.

In a matched pairs experiment the parameter of interest is the of the population of .

In testing the difference between the means of two normally distributed populations, the number of degrees of freedom associated with the unequal-variances t-test statistic usually results in a non-integer number. It is recommended that you:

When testing the equality of two population variances the number in the null hypothesis is 0.

In constructing a confidence interval estimate for the difference between two population proportions, we pool the population proportions when the populations are normally distributed.

The pooled proportion estimate is used when the proportion of successes from sample 1 equals the proportion of successes from sample 2.

In constructing a confidence interval estimate for the difference between two population proportions, we:

The F-distribution is symmetric.

Both the equal-variances and unequal variances test statistic and confidence interval estimator of $\mu _ { 1 } - \mu _ { 2 }$ require that the two populations be normally distributed.

The pooled proportion estimate is found by taking the proportion of successes from sample 1 plus the proportion of successes from sample 2.

The test statistic employed to test $H _ { 0 } : \sigma _ { 1 } ^ { 2 } / \sigma _ { 2 } ^ { 2 } = 1$ is $F = s _ { 1 } ^ { 2 } / s _ { 2 } ^ { 2 }$ is F-distributed with v₁ = n₁ - 1 and v₂ = n₂ -1 degrees of freedom if the two populations are F-distributed.

In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal, the sampling distribution of the resulting statistic is:

When we test for differences between the means of two independent populations, we can only use a two-tailed test.

The test for the equality of two population variances is based on the:

What Is Statistics

Graphical Descriptive Techniques I

Graphical Descriptive Techniques II

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

Analysis of Variance

Chi-Squared Tests Optional

Simple Linear Regression and Correlation

Multiple Regression

Filters

Exam 13: Inference About Comparing Two Populations

The equal-variances test statistic of μ1−μ2\mu _ { 1 } - \mu _ { 2 }μ1​−μ2​ is Student t-distributed with n1 + n2 -2 degrees of freedom provided that the two populations are ____________________.

In a matched pairs experiment the parameter of interest is the ____________________ of the population of ____________________.

In testing the difference between the means of two normally distributed populations, the number of degrees of freedom associated with the unequal-variances t-test statistic usually results in a non-integer number. It is recommended that you:

When testing the equality of two population variances the number in the null hypothesis is 0.

In constructing a confidence interval estimate for the difference between two population proportions, we pool the population proportions when the populations are normally distributed.

The pooled proportion estimate is used when the proportion of successes from sample 1 equals the proportion of successes from sample 2.

In constructing a confidence interval estimate for the difference between two population proportions, we:

The F-distribution is symmetric.

Both the equal-variances and unequal variances test statistic and confidence interval estimator of μ1−μ2\mu _ { 1 } - \mu _ { 2 }μ1​−μ2​ require that the two populations be normally distributed.

The pooled proportion estimate is found by taking the proportion of successes from sample 1 plus the proportion of successes from sample 2.

In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal, the sampling distribution of the resulting statistic is:

When we test for differences between the means of two independent populations, we can only use a two-tailed test.

The test for the equality of two population variances is based on the:

What Is Statistics

Graphical Descriptive Techniques I

Graphical Descriptive Techniques II

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

Analysis of Variance

Chi-Squared Tests Optional

Simple Linear Regression and Correlation

Multiple Regression

Filters

The equal-variances test statistic of $\mu _ { 1 } - \mu _ { 2 }$ is Student t-distributed with n₁ + n₂ -2 degrees of freedom provided that the two populations are ____________________.

In a matched pairs experiment the parameter of interest is the of the population of .

Both the equal-variances and unequal variances test statistic and confidence interval estimator of $\mu _ { 1 } - \mu _ { 2 }$ require that the two populations be normally distributed.