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Give null and alternative hypotheses for a population proportion, as well as sample results. Use StatKey or other technology to generate a randomization distribution and calculate a p-value. StatKey tip: Use "Test for a Single Proportion" and then "Edit Data" to enter the sample information. Hypotheses: \(H_{0}: p=0.6\) vs \(H_{a}: p>0.6\) Sample data: \(\hat{p}=52 / 80=0.65\) with \(n=80\)

Short Answer

Expert verified
The null and alternative hypotheses are \(H_{0}: p=0.6\) and \(H_{a}: p>0.6\), respectively. The sample proportion is \(\hat{p}=52 / 80=0.65\) from \(n=80\) observations. A randomization distribution needs to be generated using software followed by the calculation of the p-value, which gives the chance of observing what we did if the null hypothesis was true.

Step by step solution

01

State the Hypotheses

The null hypothesis (\(H_{0}\)) is that the population proportion \(p\) equals 0.6, while the alternative hypothesis (\(H_{a}\)) is that the population proportion \(p\) is greater than 0.6. In other words, \(H_{0}: p=0.6\) and \(H_{a}: p>0.6\).
02

Analyze Sample Data

The sample data are given as a proportion: \(\hat{p} = 52/80 = 0.65\). This sample data will be used to conduct the hypothesis test.
03

Generate Randomization Distribution

Using StatKey or similar software, generate a randomization distribution. In StatKey, select 'Test for a Single Proportion', then 'Edit Data' to enter the sample information. Then, use the software to create the randomization distribution, which models what might happen if the null hypothesis is true.
04

Calculate p-value

Calculate the p-value, which is the probability under the null hypothesis of obtaining a result as extreme as, or more extreme than, the observed result. This p-value can be obtained by counting what proportion of the simulated randomization statistics are greater than or equal to the observed sample proportion of 0.65. The p-value is then this proportion.

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Most popular questions from this chapter

Flying Home for the Holidays, On Time In Exercise 4.115 on page \(302,\) we compared the average difference between actual and scheduled arrival times for December flights on two major airlines: Delta and United. Suppose now that we are only interested in the proportion of flights arriving more than 30 minutes after the scheduled time. Of the 1,000 Delta flights, 67 arrived more than 30 minutes late, and of the 1,000 United flights, 160 arrived more than 30 minutes late. We are testing to see if this provides evidence to conclude that the proportion of flights that are over 30 minutes late is different between flying United or Delta. (a) State the null and alternative hypothesis. (b) What statistic will be recorded for each of the simulated samples to create the randomization distribution? What is the value of that statistic for the observed sample? (c) Use StatKey or other technology to create a randomization distribution. Estimate the p-value for the observed statistic found in part (b). (d) At a significance level of \(\alpha=0.01\), what is the conclusion of the test? Interpret in context. (e) Now assume we had only collected samples of size \(75,\) but got essentially the same proportions (5/75 late flights for Delta and \(12 / 75\) late flights for United). Repeating steps (b) through (d) on these smaller samples, do you come to the same conclusion?

The same sample statistic is used to test a hypothesis, using different sample sizes. In each case, use StatKey or other technology to find the p-value and indicate whether the results are significant at a \(5 \%\) level. Which sample size provides the strongest evidence for the alternative hypothesis? Testing \(H_{0}: p=0.5\) vs \(H_{a}: p>0.5\) using \(\hat{p}=0.58\) with each of the following sample sizes: (a) \(\hat{p}=29 / 50=0.58\) (b) \(\hat{p}=290 / 500=0.58\)

In Exercise 4.16 on page 268 , we describe an observational study investigating a possible relationship between exposure to organophosphate pesticides as measured in urinary metabolites (DAP) and diagnosis of ADHD (attention-deficit/hyperactivity disorder). In reporting the results of this study, the authors \(^{28}\) make the following statements: \- "The threshold for statistical significance was set at \(P<.05 . "\) \- "The odds of meeting the \(\ldots\) criteria for \(\mathrm{ADHD}\) increased with the urinary concentrations of total DAP metabolites" \- "The association was statistically significant." (a) What can we conclude about the p-value obtained in analyzing the data? (b) Based on these statements, can we distinguish whether the evidence of association is very strong vs moderately strong? Why or why not? (c) Can we conclude that exposure to pesticides is related to the likelihood of an ADHD diagnosis? (d) Can we conclude that exposure to pesticides causes more cases of ADHD? Why or why not?

A statistics instructor would like to ask "clicker" questions that about \(80 \%\) of her students in a large lecture class will get correct. A higher proportion would be too easy and a lower proportion might discourage students. Suppose that she tries a sample of questions and receives 76 correct answers and 24 incorrect answers among 100 responses. The hypotheses of interest are \(H_{0}: p=0.80\) vs \(H_{a}: p \neq 0.80 .\) Discuss whether or not the methods described below would be appropriate ways to generate randomization samples in this setting. Explain your reasoning in each case. (a) Sample 100 answers (with replacement) from the original student responses. Count the number of correct responses. (b) Sample 100 answers (with replacement) from a set consisting of 8 correct responses and 2 incorrect responses. Count the number of correct mses.

Exercise 4.26 discusses a sample of households in the US. We are interested in determining whether or not there is a linear relationship between household income and number of children. (a) Define the relevant parameter(s) and state the null and alternative hypotheses. (b) Which sample correlation shows more evidence of a relationship, \(r=0.25\) or \(r=0.75 ?\) (c) Which sample correlation shows more evidence of a relationship, \(r=0.50\) or \(r=-0.50 ?\)

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