Exam 10: Statistical Inferences Based on Two Samples

Using a 90 percent confidence interval of [-.0076,.0276] for the difference between the proportions of failures in factory 1 and factory 2,where can we reject the null hypothesis at α = .10?

When testing H₀: μ₁ - μ₂ = 2,H_A: μ₁ - μ₂> 2,where what is the test statistic? (Assume unequal variances. )

A coffee shop franchise owner is looking at two possible locations for a new shop.To help him decide,he looks at the number of pedestrians that go by each of the two locations in one-hour segments.At location A,counts are taken for 35 one-hour units,with a mean number of pedestrians of 421 and a sample standard deviation of 122.At the second location (B),counts are taken for 50 one-hour units,with a mean number of pedestrians of 347 and a sample standard deviation of 85.Assume the two populations variances are not known but are equal.Testing the claim that both sites have the same mean number of pedestrians at α = .01,what do you conclude?

Suppose that a realtor is interested in comparing the price of midrange homes in two cities in a midwestern state.She conducts a small survey in the two cities,looking at the price of midrange homes.Assume equal population variances. Set up the alternative hypothesis to test the claim that there is a difference in the mean price of midrange homes of the two cities.

A financial analyst working for a financial consulting company wishes to find evidence that the average price-to-earnings ratio in the consumer industry is higher than the average price-to-earnings ratio in the banking industry.The alternative hypothesis is:

A marketing research company surveyed grocery shoppers on the East Coast and West Coast to find the percentage of the customers who prefer chicken to other meat.The data are given below. Is the proportion of customers who prefer chicken the same for the two regions? Test at α = .10.

When testing H₀: σ₁²= σ₁²,H_A: σ₁²> σ₂² at α = .01,where n₁ = 5,n₂ = 6,s₁² = 15,750,and s₂² = 10,920,what critical value do we use?

In an opinion survey,a random sample of 1000 adults from the United States and 1000 adults from Germany were asked whether they supported the death penalty.590 American adults and 560 German adults indicated that they supported the death penalty.The researcher wants to know whether there is sufficient evidence to conclude that the proportion of adults who support the death penalty is higher in the United States than in Germany.What is the rejection point (critical value of the test statistic)at α = .05?

Suppose that a realtor is interested in comparing the price of midrange homes in two cities in a midwestern state.She conducts a small survey in the two cities,looking at the price of midrange homes.Assume equal population variances. Calculate the 95 percent confidence interval.

A test of driving ability is given to a random sample of 10 student drivers before and after they complete a formal driver education course.Results follow. Test the hypothesis that there is no difference between the before-class scores and the after-class scores at α = .05.

Find a 95 percent confidence interval for μ₁ - μ₂,where (Assume equal population variances. )

When comparing the variances of two normally distributed populations using independent random samples,the correct test statistic to use is __________.

Two independent samples selected from two normally distributed populations have variances of σ₁² and σ₂² with n₁ = 10 and n₂ = 15.The degrees of freedom for the F distribution when testing the equality of the two population variances are:

In testing the difference between the means of two normally distributed populations using independent random samples,the alternative hypothesis always indicates no differences between the two specified means.

An independent samples experiment is an experiment in which there is no relationship between the measurements in the different samples.

In order to test the effectiveness of a drug called XZR designed to reduce cholesterol levels,the cholesterol levels of 9 heart patients are measured before they are given the drug.The same 9 patients use XZR for two continuous months.After two months of continuous use,the cholesterol levels are measured again.The comparison of cholesterol levels before versus after the administration of the drug is an example of testing the difference between two ____________.

An experiment in which two different measurements are taken on the same units and inferences are made using the differences between the pairs of measurements is a(n)______ experiment.

We use the following data for a test of the equality of variances for two populations at α = .10.Sample 1 is randomly selected from population 1 and sample 2 is randomly selected from population 2.Can we reject H₀ at α = .10?

In an opinion survey,a random sample of 1000 adults from the United States and 1000 adults from Germany were asked whether they supported the death penalty.590 American adults and 560 German adults indicated that they supported the death penalty.The researcher wants to know whether there is sufficient evidence to conclude that the proportion of adults who support the death penalty is higher in the United States than in Germany.What is the decision at α = .10?

In testing the difference between two means from two independent populations,the sample sizes do not have to be equal.