Deliverable 5 - Hypothesis Tests for Two Samples

Instructions: The following worksheets describe two problems – the first problem is for independent samples and the second problem is for dependent samples. Your job is to demonstrate the solution to each scenario by showing how to work through each problem in detail. You are expected to explain all of the steps in your own words.

Independent Samples

A researcher conducted a test to learn the effect of lead levels in human bodies. He collected the IQ scores for a random sample of subjects with low lead levels in their blood and another random sample of subjects with high lead levels in their blood. The summary of finding is listed below. Use a 0.05 significance level to test the claim that the mean IQ score of people with low lead levels is higher than the mean IQ score of people with high lead levels.

We do not know the values of the population standard deviations.

Low Lead Level          High Lead Level

n1                    60        n2        20

                                    91.44               82.7

s1                     17.45   s2         9.68

1. Write the hypotheses in symbolic form, determine if the test is right-tailed, left-tailed, or two tailed and explain why.
2. Calculate the critical value, the test statistic, and p-value. Show calculations below.

Critical Value:

Test Statistic:

p-value:

1. Make a decision about the null hypothesis and explain your reasoning, then make a conclusion about the claim in nontechnical terms.

Dependent Samples

The Harry Potter books and movies made a lot of money. A fan wanted to learn which of his favorite movies made more money. He collected the amounts grossed in millions during the first few days of releases of the movies Harry Potter and the Half-Blood Prince and Harry Potter and the Order of the Phoenix. Use a 0.05 significance level to test his claim that the Prince movie did better at the box office.

Use the p-value method to determine whether or not to reject the null hypothesis and state your conclusion.

Days of Release/Book       Phoenix           Prince

1                                        44.3                 58.2

2                                        18.4                 22.0

3                                        25.8                 28.6

4                                        28.3                 29.2

5                                        22.0                 21.8

6                                        9.9                   10.7

7                                        9.3                   9.4

8                                        8.4                   7.5

9                                        7.6                   6.9

10                                      10.2                 9.2

 

1. Write the hypotheses in symbolic form, determine if the test is right-tailed, left-tailed, or two tailed and explain why.
2. Calculate the critical value, the test statistic, and p-value. Show calculations below.

Critical Value:

Test Statistic:

p-value:

 6. Make a decision about the null hypothesis and explain your reasoning, then make a conclusion about the claim in nontechnical terms.