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Ch. 8 - Hypothesis Testing with Two Samples
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook
Chapter 8, Problem 8.3.18f

Testing the Difference Between Two Means (f) interpret the decision in the context of the original claim. Assume the samples are random and dependent, and the populations are normally distributed.
[APPLET] Passing Play Percentages The passing play percentages of 10 randomly selected NCAA Division 1A college football teams for home and away games in the 2020–2021 season are shown in the table. At , α=0.20 is there enough evidence to support the claim that passing play percentage is different for home and away games? (Source: TeamRankings)
Table comparing home and away passing play percentages for 10 NCAA Division 1A college football teams.

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Step 1: Identify the problem as a paired-sample t-test since the data involves dependent samples (home and away passing play percentages for the same teams). The goal is to test if there is a significant difference between the means of the two conditions.
Step 2: State the null hypothesis (H₀) and the alternative hypothesis (H₁). H₀: The mean difference in passing play percentages between home and away games is 0 (μd = 0). H₁: The mean difference in passing play percentages between home and away games is not 0 (μd ≠ 0).
Step 3: Calculate the differences (d) between the home and away passing play percentages for each team. Then, compute the mean of these differences (d̄) and the standard deviation of the differences (s_d).
Step 4: Use the formula for the test statistic t = (d̄ - μd) / (s_d / √n), where μd = 0 under the null hypothesis, n is the number of paired observations (10 in this case), and s_d is the standard deviation of the differences. Compute the t-value.
Step 5: Compare the calculated t-value to the critical t-value from the t-distribution table at α = 0.20 with degrees of freedom df = n - 1 (df = 9). If the absolute value of the t-value exceeds the critical value, reject the null hypothesis. Otherwise, fail to reject the null hypothesis. Interpret the decision in the context of the original claim.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Hypothesis Testing

Hypothesis testing is a statistical method used to make decisions about population parameters based on sample data. It involves formulating a null hypothesis (H0) and an alternative hypothesis (H1), then using sample statistics to determine whether to reject H0. In this context, the null hypothesis would state that there is no difference in passing play percentages between home and away games.
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Step 1: Write Hypotheses

Dependent Samples

Dependent samples refer to pairs of observations that are related or matched in some way, such as measurements taken from the same subjects under different conditions. In this case, the passing play percentages for home and away games are dependent because they come from the same teams. This relationship affects the choice of statistical tests used to analyze the data.
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Significance Level (α)

The significance level, denoted as α, is the threshold for determining whether to reject the null hypothesis in hypothesis testing. It represents the probability of making a Type I error, which occurs when the null hypothesis is incorrectly rejected. In this scenario, α is set at 0.20, indicating a willingness to accept a 20% chance of concluding that there is a difference in passing play percentages when there is none.
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Related Practice
Textbook Question

Testing the Difference Between Two Means (e) decide whether to reject or fail to reject the null hypothesis, Assume the samples are random and dependent, and the populations are normally distributed.

[APPLET] Migraines

A researcher claims that injections of onabotulinumtoxinA reduce the number of days per month that chronic migraine sufferers have headaches. The table shows the number of days chronic migraine sufferers suffered migraines before and after using the treatment. At , α= 0.01 is there enough evidence to support the researcher’s claim? (Adapted from Journal of Headache and Pain)

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Textbook Question

Testing the Difference Between Two Means (f) interpret the decision in the context of the original claim. Assume the samples are random and dependent, and the populations are normally distributed.

[APPLET] Migraines

A researcher claims that injections of onabotulinumtoxinA reduce the number of days per month that chronic migraine sufferers have headaches. The table shows the number of days chronic migraine sufferers suffered migraines before and after using the treatment. At , α= 0.01 is there enough evidence to support the researcher’s claim? (Adapted from Journal of Headache and Pain)

53
views
Textbook Question

Testing the Difference Between Two Means, (e) interpret the decision in the context of the original claim. 

Assume the samples are random and independent, and the populations are normally distributed.

Transactions

 A magazine claims that the mean amount spent by a customer at Burger Stop is greater than the mean amount spent by a customer at Fry World. The results for samples of customer transactions for the two fast food restaurants are shown at the left. At , α=0.05 can you support the magazine’s claim? Assume the population variances are equal.

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Textbook Question

Testing the Difference Between Two Means (f) interpret the decision in the context of the original claim. Assume the samples are random and dependent, and the populations are normally distributed.

Interval Training

A researcher claims that sprint interval training improves running performance in trained athletes. The table shows the maximum aerobic speed (MAS), in kilometers per hour, of trained athletes before and after six sessions of sprint interval training. At , α=0.10 is there enough evidence to support the researcher’s claim? (Adapted from National Strength and Conditioning Association)

53
views
Textbook Question

Testing the Difference Between Two Means (e) decide whether to reject or fail to reject the null hypothesis. Assume the samples are random and dependent, and the populations are normally distributed.

[APPLET] Passing Play Percentages The passing play percentages of 10 randomly selected NCAA Division 1A college football teams for home and away games in the 2020–2021 season are shown in the table. At , α=0.20 is there enough evidence to support the claim that passing play percentage is different for home and away games? (Source: TeamRankings)


51
views