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Testing Claims About Proportions. In Exercises 9鈥32, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, or critical value(s), then state the conclusion about the null hypothesis, as well as the final conclusion that addresses the original claim. Use the P-value method unless your instructor specifies otherwise. Use the normal distribution as an approximation to the binomial distribution, as described in Part 1 of this section.

Medical Malpractice In a study of 1228 randomly selected medical malpractice lawsuits, it was found that 856 of them were dropped or dismissed (based on data from the Physicians Insurers Association of America). Use a 0.01 significance level to test the claim that most medical malpractice lawsuits are dropped or dismissed. Should this be comforting to physicians?

Short Answer

Expert verified

Nullhypothesis: The proportion of medical malpractice lawsuits subjects dropped or dismissed is equal to 50%.

Alternativehypothesis: The proportion of medical malpractice lawsuits subjects dropped or dismissed is more than 50%.

Test Statistic: 13.807

Critical Value: 2.3263

P-Value: 0.000

The null hypothesis is rejected.

There is enough evidence to support the claim that most medical malpractice lawsuits subjects were dropped or dismissed.

Since most malpractice lawsuits are either dropped or dismissed, it will be quite comforting for doctors and physicians as they would avoid any pain due to legal proceedings.

Step by step solution

01

Given information

Out of 1228 randomly selected medical malpractice lawsuits, 856 of them were dropped or dismissed.

02

Hypotheses

The null hypothesis is written as follows:

The proportion of medical malpractice lawsuits subjects who were dropped or dismissedequals50%.

H0:p=0.5

The alternative hypothesis is written as follows:

The proportion of medical malpractice lawsuits subjects dropped or dismissed is more than 50%.

H0:p=0.5

The test is right-tailed.

03

Sample size, sample proportion, and population proportion

The sample size equals n=1228.

The sample proportion of medical malpractice lawsuits subjects dropped or dismissed isas follows:

p^=8561228=0.697

The population proportion of medical malpractice lawsuits subjects dropped or dismissed is equal to 0.5.

04

Test statistic

The value of the test statistic is computed below:

z=p^-ppqn=0.697-0.50.51-0.51228=13.807

Thus, z=13.807.

05

Critical value and p-value

Referring to the standard normal distribution table, the critical value of z at =0.01 for a right-tailed test equals2.3263.

Referring to the standard normal distribution table, the p-value for the test statistic value of 13.807 equals0.000.

Since the p-value is less than 0.05, the null hypothesis is rejected.

06

Conclusion of the test

There is enough evidence to support the claim that the proportion of medical malpractice lawsuits subjects dropped or dismissed is greater than 0.5.

Since most malpractice lawsuits are either dropped or dismissed, it should be comforting for the physicians as they can be relieved without any trial.

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Most popular questions from this chapter

In Exercises 13鈥16, refer to the exercise identified and find the value of the test statistic. (Refer to Table 8-2 on page 362 to select the correct expression for evaluating the test statistic.)

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Testing Claims About Proportions. In Exercises 9鈥32, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, or critical value(s), then state the conclusion about the null hypothesis, as well as the final conclusion that addresses the original claim. Use the P-value method unless your instructor specifies otherwise. Use the normal distribution as an approximation to the binomial distribution, as described in Part 1 of this section.

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Testing Claims About Proportions. In Exercises 9鈥32, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, or critical value(s), then state the conclusion about the null hypothesis, as well as the final conclusion that addresses the original claim. Use the P-value method unless your instructor specifies otherwise. Use the normal distribution as an approximation to the binomial distribution, as described in Part 1 of this section.

Cell Phones and Cancer In a study of 420,095 Danish cell phone users, 135 subjects developed cancer of the brain or nervous system (based on data from the Journal of the National Cancer Institute as reported in USA Today). Test the claim of a somewhat common belief that such cancers are affected by cell phone use. That is, test the claim that cell phone users develop cancer of the brain or nervous system at a rate that is different from the rate of 0.0340% for people who do not use cell phones. Because this issue has such great importance, use a 0.005 significance level. Based on these results, should cell phone users be concerned about cancer of the brain or nervous system?

Calculating Power Consider a hypothesis test of the claim that the Ericsson method of gender selection is effective in increasing the likelihood of having a baby girl, so that the claim is p>0.5. Assume that a significance level of = 0.05 is used, and the sample is a simple random sample of size n = 64.

a. Assuming that the true population proportion is 0.65, find the power of the test, which is the probability of rejecting the null hypothesis when it is false. (Hint: With a 0.05 significance level, the critical value is z = 1.645, so any test statistic in the right tail of the accompanying top graph is in the rejection region where the claim is supported. Find the sample proportion in the top graph, and use it to find the power shown in the bottom graph.)

b. Explain why the green-shaded region of the bottom graph represents the power of the test.

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