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Ch. 9 - Inferences from Two Samples
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446Not the one you use?Change textbook
Chapter 9, Problem 9.5.6

In Exercises 5–8, use (a) randomization and (b) bootstrapping for the indicated exercise from Section 9-1. Compare the results to those obtained in the original exercise.


Exercise 8 in Section 9-1 “Tennis Challenges”

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1
Identify the original problem in Exercise 8 of Section 9-1, which involves analyzing data related to tennis challenges. This typically includes determining whether the success rate of challenges is statistically significant or not.
For part (a), randomization: Randomly shuffle the observed data (e.g., success and failure outcomes of tennis challenges) to create a distribution under the null hypothesis. This involves assuming that the observed outcomes are due to random chance. Calculate the test statistic (e.g., proportion of successful challenges) for each randomization iteration.
For part (b), bootstrapping: Use the observed data to create a bootstrap sample by resampling with replacement. Calculate the test statistic (e.g., proportion of successful challenges) for each bootstrap sample. Repeat this process many times to build a bootstrap distribution of the test statistic.
Compare the results: Analyze the distributions obtained from randomization and bootstrapping. Compare these results to the original exercise's findings to determine if the conclusions are consistent across methods.
Interpret the findings: Discuss whether the randomization and bootstrapping methods support the original conclusions about the success rate of tennis challenges. Highlight any differences or similarities in the results.

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Key Concepts

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

Randomization

Randomization is a statistical technique used to eliminate bias by randomly assigning subjects to different groups or treatments. This process ensures that each participant has an equal chance of being placed in any group, which helps to create comparable groups and allows for valid inferences about the effects of treatments. In the context of the exercise, randomization can be applied to simulate different scenarios or outcomes based on the original data.
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Intro to Random Variables & Probability Distributions

Bootstrapping

Bootstrapping is a resampling method that involves repeatedly drawing samples from a dataset with replacement to estimate the distribution of a statistic. This technique allows statisticians to assess the variability of a statistic without making strong parametric assumptions about the underlying population. In the context of the exercise, bootstrapping can be used to generate confidence intervals or to test hypotheses based on the original data.

Comparison of Results

Comparing results involves analyzing the outcomes obtained from different statistical methods or approaches to determine their similarities and differences. In this case, it refers to evaluating the results from the original exercise against those derived from randomization and bootstrapping. This comparison helps to assess the robustness of the findings and provides insights into the reliability of the statistical methods used.
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Difference in Proportions: Hypothesis Tests Example 1
Related Practice
Textbook Question

Body Temperatures Listed below are body temperatures from six different subjects measured at two different times in a day (from Data Set 5 “Body Temperatures” in Appendix B).


a. Are the two sets of data independent or dependent? Explain.


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Textbook Question

Finding Critical Values

In Exercises 17–20, refer to the information in the given exercise and use a 0.05 significance level for the following.


a. Find the critical value(s).

b. Should we reject H0 or should we fail to reject H0?


Exercise 14

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Textbook Question

Testing Effects of Alcohol Researchers conducted an experiment to test the effects of alcohol. Errors were recorded in a test of visual and motor skills for a treatment group of 22 people who drank ethanol and another group of 22 people given a placebo. The errors for the treatment group have a standard deviation of 2.20, and the errors for the placebo group have a standard deviation of 0.72 (based on data from “Effects of Alcohol Intoxication on Risk Taking, Strategy, and Error Rate in Visuomotor Performance,” by Streufert et al., Journal of Applied Psychology, Vol. 77, No. 4). Use a 0.05 significance level to test the claim that both groups have the same amount of variation among the errors.

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Textbook Question

In Exercises 5–8, use (a) randomization and (b) bootstrapping for the indicated exercise from Section 9-1. Compare the results to those obtained in the original exercise.


Exercise 9 in Section 9-1 “Cell Phones and Handedness”


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Textbook Question

Degrees of Freedom For Example 1, we used df=smaller of n1-1 and n2-1 we got df=11 and the corresponding critical value is t=-1.796 (found from Table A-4). If we calculate df using Formula 9-1, we get df=19.370 and the corresponding critical value is t=-1.727 How is using the critical value of t=-1.796 “more conservative” than using the critical value of t=-1.727

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Textbook Question

In Exercises 17–24, use the indicated Data Sets from Appendix B. The complete data sets can be found at www.TriolaStats.com. Assume that the paired sample data are simple random samples and the differences have a distribution that is approximately normal.

Measured and Reported Weights Repeat Example 1 using all of the 2784 measured and reported weights of males listed in Data Set 4 “Measured and Reported” in Appendix B. Did the larger data set have much of an effect on the results?

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