Suppose a hospital wants to evaluate the effectiveness of a new treatment for a certain disease. They randomly assign 200 patients to receive the new treatment and another 200 patients to receive the standard treatment. If the response rate for the new treatment is 60% and for the standard treatment is 40%, what is the probability that the difference in response rates between the two treatments is statistically significant at a significance level of 0.05?
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- Researchers investigate how the presence of cell phones influence the quality of human interaction. Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room. Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment. What statistical test is appropriate?A union of restaurant and foodservice workers would like to estimate this year's mean hourly wage, u, of foodservice workers in the U.S. Last year's mean hourly wage was $8.25, and there is reason to believe that this year's value is less than last year's. The union decides to do a statistical test to see if the value has indeed decreased. The union chooses a random sample of this year's wages, computes the mean of the sample to be $7.98, and computes the standard deviation of the sample to be $1.25. Based on this information, answer the questions below. What are the null hypothesis (H) and the alternative hypothesis (H,) that should be used for the test? |Ho: u is ? H: u is ? v|? ? In the context of this test, what is a Type I error? v the hypothesis that u is ? A Type I error is ? fact, u is ? v when, in Suppose that the union decides not to reject the null hypothesis. What sort of error might it be making? ?10.In a study we reject Ho Which of the following statements are incorrect and why? (a) "Now we know that H, is false." (b) "We have proof that our sample mean represents a particular p." (c) "We have proof that the independent variable causes scores to change as predicted." (d) "It is not pos- sible that the difference between X and u is due to sampling error." (e) "We have evidence that the predicted relationship does
- Teenagers who do not sleep well or long enough may have a higher risk of raised blood pressure, which could lead to cardiovascular disease later in life. The odds of raised blood pressure increase 3.5 times for those who have trouble falling asleep at night or who wake up too early and 2.5 times for those with sleeping periods of fewer than 6.5 hours. A health psychologist is interested in studying teenagers who have diastolic blood pressure scores in the top 20%. Diastolic blood pressure scores for teenagers follow a normal distribution with μ = 72 and σ = 10. Use the Distributions tool to help answer the questions that follow. The minimum z-score necessary to be in the top 20% of the diastolic blood pressure distribution is z =0.842 . Use this z-score to determine X, the corresponding diastolic blood pressure score. X = 80.42 This score, X, is the 80th percentile of diastolic blood pressure scores among teenagers. The percentile rank of this score is 80%…An analyst from the UK Office of Statistics is investigating the provision of social support services throughout the city of Manchester. For each borough in the city they will establish the required level of support based on the percentage of residents below the poverty line. They take a random sample of 122 individuals in the borough of Bury and find that 25 have annual net-income below the poverty line. The analyst will decide to provide Bury with additional social services support if the sample data provides sufficient evidence that the true proportion of people living below poverty line is greater than 17%. A test of hypothesis is conducted. What is the null hypothesis? The true proportion of Bury inhabitants below the poverty line is lower than 0.17. The true proportion of Bury inhabitants below the poverty line is greater than 0.17. The sample proportion of Bury inhabitants below the poverty line is lower than 0.17. The sample proportion of Bury inhabitants below the poverty…A national organization that conducts research on the cost and quality of health care in the U.S. reported that, in 2012, U.S. families spent an average of $9,590 on health care expenses. Suppose you decide to test whetherthe average in 2015 is greater than the average in 2012. After conducting the appropriate statistical test, you find a P-value of 0.022. If the level of significance is 0.05, which of the following is the best interpretation of the P-value? a. The P-value of 0.022 indicates that there is a 2.2% chance that the 2015 average is greater than the average amount spent in 2012.b. The P-value of 0.022 provides weak evidence that the average in 2015 average is greater than the average amount spent in 2012.c. The P-value of 0.022 provides strong evidence that the 2015 average is greater than the average amount spent in 2012.d. The P-value of 0.022 indicates that there is a very low probability that the 2015 average is different than average amount spent in 2012.
- Acne is a common skin disease that affects most adolescents and can continue into adulthood. A study compared the effectiveness of three acne treatments and a placebo, all in gel form, applied twice daily for 12 weeks. The study's 517 teenage volunteers were randomly assigned to one of the four treatments. Success was assessed as clear or almost clear skin at the end of the 12 week period. The results of the study can be seen in the table below. Using the appropriate statistical test, determine if there is significant evidence that the four treatments perform differently. If so, how do they compare.A teaching assistant for a psychology course is curious about what factors are associated with higher final grades in the course. She finds that students who read the textbook tend to have higher final grades in the course. She finds that students who watch the lecture videos tend to have higher final grades in the course. Lastly, she finds that students who read the textbook and watch the lecture videos tend to have the highest grades in the course. Assuming that any difference is statistically significant, which of the following best characterizes these results? 1 main effect and O interaction effects 1 main effect and 1 interaction effect O main effects and O interaction effects 2 main effects and 1 interaction effect O main effects and 1 interaction effect 2 main effects and O interaction effectsA researcher intends to estimate the effect of a drug on the scores of human subjects performing a task of psychomotor coordination. The members of a random sample of 9 subjects were given the drug prior to testing. The mean score in this group was 9.07, and the sample variance was 17.68. An independent random sample of 10 subjects was used as a control group and given a placebo prior to testing. The mean score in this control group was 15.21, and the sample variance was 27.48. Assuming that the population distributions are normal with equal variances, find a 90% confidence interval for the difference between the population mean scores The confidence interval is<, -,O (Round to two decimal places as needed.)
- In college, talented runners may join a cross-country team. Runners tend to run their best times when they run even splits. Even splits occur when the runners maintain an even pace throughout the race. The cross-country coach wants to estimate the typical variability in his best runner's 1-mile splits. He takes a random sample of 25 of this runner's mile splits and finds that this runner's mean 1-mile split is 5.44 minutes per mile, with a standard deviation of 0.14 minutes per mile. This runner's 1-mile splits follow a normal distribution. (a) Find the chi-square critical values XL² and Xu² to be used in constructing a 95% confidence interval for the true population standard deviation. (Round your answers to two decimal places.) XL²= XU²= (b) Find the 95% confidence interval for the true variability in his best runner's 1-mile splits. (Round your answers to three decimal places.) lower bound and the upper boundThe drug Ritalin is designed to stimulate the central nervous system. In a random sample of 252 boys aged ten – twelve years old, it was found that 44 of the boys were taking Ritalin. It is known that the proportion of all boys aged 13 – 15 who take Ritalin is 24%. A researcher claims that the population proportions of boys who take Ritalin aged 10 – 12 is different than boys aged 13 – 15. Can you support this claim at the 5% significance level? a. Conduct a hypothesis test to test the claim at the 5% significance level. Be sure to state you Ho and Ha, your test statistic and p-value, whether or not you reject Ho and whether you support the claim. b. Show that you can use the large sample methodology. c. Write a complete sentence describing what a Type I error is in context.6. A clinical trial is conducted comparing a new pain reliever for arthritis to a placebo. Participants are randomly assigned to receive the new treatment or a placebo and the outcome is pain relief within 30 minutes. The data are shown in Table 7–54. Is there a significant difference in the proportions of patients reporting pain relief? Run the test at a 5% level of significance.