Exam 13: Inference About Comparing Two Populations

Starting Salary In testing the hypotheses vs. , two random samples from two populations of college of business graduates majoring in global marketing and international business produced the following statistics regarding their starting salaries (in $1000s): , , , , , and .(Assume the salaries have normal distributions.) -{Starting Salary Narrative} Estimate with 95% confidence the difference between the two population means.

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:

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

In constructing a confidence interval estimate for the difference between two population proportions, we ____________________ (always/sometimes/never) pool the population proportions.

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. -{Mass Production Line Narrative} What is the p-value of the test? Explain how to use it for testing the hypotheses.

Which of the following statements is false for an F-distribution?

The symbol refers to:

In comparing two population means of interval data, we must decide whether the samples are independent (in which case the parameter of interest is ) or matched pairs (in which case the parameter is $\mu$ _D) in order to select the correct test statistic.

Starting Salary In testing the hypotheses vs. , two random samples from two populations of college of business graduates majoring in global marketing and international business produced the following statistics regarding their starting salaries (in $1000s): , , , , , and .(Assume the salaries have normal distributions.) -{Starting Salary Narrative} Explain how to use the 95% confidence interval to test the hypotheses at $\alpha$ = .05.

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:

Senatorial Election A political poll immediately prior to a senatorial election reveals that 145 out of 250 male voters and 105 out of 200 female voters intend to vote for the Democrat candidate. -{Senatorial Election Narrative} Estimate with 95% confidence the difference in the proportion of male and female voters who intend to vote for the Democrat candidate.

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. -{Mass Production Line Narrative} Estimate with 95% confidence the difference in population proportions.

A political analyst in Iowa 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 ____________________ samples.

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.

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 sampling distribution of the ratio of two (independent) sample variances is said to be ____________________ distributed.

If the sample sizes are large enough so the conditions are met, the difference between two sample proportions has an approximate ____________________ distribution.

A behaviorist has performed the following experiment.For each of 10 sets of identical twins who were born 30 years ago, he recorded their annual incomes, according to which twin was born first.The results (in $1,000s) are shown below.Can he infer at 5% significance level that there is a difference in income between the twins?

Speed Limits Violation Do out-of-state motorists violate the speed limit more frequently than in-state motorists? This vital question was addressed by the highway patrol in a large eastern state.A random sample of the speeds of 2,500 randomly selected cars was categorized according to whether the car was registered in the state or in some other state and whether or not the car was violating the speed limit.The data follow. -{Speed Limits Violation Narrative} Briefly describe what the interval estimate tells you.

Two samples of sizes 25 and 20 are independently drawn from two normal populations, where the unknown population variances are assumed to be equal.The number of degrees of freedom of the equal-variances t-test statistic is 44.