An article that appeared in the British Medical Journal (2010) presented the results of a randomized experiment conducted by researcher Jeremy Groves, whose objective was to determine whether the weight of his bicycle could affect his travel time to work. On each of 56 days (from mid-January to mid-July 2010), Groves tossed a £1 coin to decide whether he would be biking to work on his carbon frame (lighter) bicycle that weighed 20.9 lbs or on his steel frame (heavier) bicycle that weighed 29.75 lbs. He then recorded the commute time (in minutes) for each trip. Here are the summary statistics for his data: Bike Type Sample size Sample average Sample SD Carbon frame (lighter) 26 108.34 min 6.25 min Steel frame (heavier) 30 107.81 min 3.89 min Which of the following applets would be most appropriate to use, in the context of this study? One Mean One Proportion Multiple Proportions Multiple Means Matched Pairs

A random sample of n1 = 157 people ages 16 to 19 were taken from the island of Oahu, Hawaii, and 12 were found to be high school dropouts. Another random sample of n2 = 129 people ages 16 to 19 were taken from Sweetwater County, Wyoming, and 6 were found to be high school dropouts. Do these data indicate that the population proportion of high school dropouts on Oahu is different (either way) from that of Sweetwater County? Use a 1% level of significance. (a) What is the level of significance?   (b)What is the value of the sample test statistic? (Test the difference p1 − p2. Do not use rounded values. Round your final answer to two decimal places.) (c) Find (or estimate) the P-value. (Round your answer to four decimal places.)

Suppose that 73.2% of all adults with type 2 diabetes also suffer from hypertension. After developing a new drug to treat type 2 diabetes, a team of researchers at a pharmaceutical company wanted to know if their drug had any impact on the incidence of hypertension for diabetics who took their drug. The researchers selected a random sample of 1000 participants who had been taking their drug as part of a recent large-scale clinical trial and found that 718 suffered from hypertension. The researchers want to use a one‑sample ?z‑test for a population proportion to see if the proportion of type 2 diabetics who have hypertension while taking their new drug, ?p, is different from the proportion of all type 2 diabetics who have hypertension. They decide to use a significance level of ?=0.01α=0.01. Determine the value of the ?z‑test statistic. Give your answer precise to two decimal places. Determine the ?-valueP-value for this test. Give your answer precise to three decimal places.

The authors of a research article were interested in the effect on female viewers of watching movies in which female heroines were portrayed in roles that focus on their sex appeal. They carried out an experiment in which female college students were assigned at random to one of two experimental groups. The 24 women in one group watched 13 minutes of scenes from a certain superhero film series and then responded to a questionnaire designed to measure body esteem. Lower scores on this measure correspond to lower body satisfaction. The 27 women in the other group (the control group) did not watch any video prior to responding to the questionnaire measuring body esteem. For the women who watched the video, the mean body esteem score was 4.44 and the standard deviation was 1.02. For the women in the control group, the mean body esteem score was 5.07 and the standard deviation was 0.98. For purposes of this exercise, you may assume that the distribution of body esteem scores for each of the…

W. Thomas Boyce, a professor and pediatrician at the University of British Columbia, Vancouver, has studied interactions between individual differences in physiology and differences in experience in determining health and well-being. Dr. Boyce found that some children are more sensitive to their environments. They do exceptionally well when the environment is supportive but are much more likely to have mental and physical health problems when the environment has challenges. You decide to do a similar study, conducting a factorial experiment to test the effectiveness of one environmental factor and one physiological factor on a physical health outcome. As the environmental factor, you choose two levels of stressful life events. As the physiological factor, you choose three levels of immune reactivity. The outcome is number of respiratory illnesses in the previous 12 months, and the research participants are kindergartners.

A simple random sample of size n = 56 is obtained from a population that is skewed left with µ = 81 and o= 8. Does the population need to be normally distributed for the sampling distribution of x to be approximately normally distributed? Why? What is the sampling distribution of X? Does the population need to be normally distributed for the sampling distribution of x to be approximately normally distributed? Why? A. No. The central limit theorem states that regardless of the shape of the underlying population, the sampling distribution of x becomes approximately normal as the sample size, n, increases. B. Yes. The central limit theorem states that only for underlying populations that are normal is the shape of the sampling distribution of x normal, regardless of the sample size, n. C. Yes. The central limit theorem states that the sampling variability of nonnormal populations will increase as the sample size increases. D. No. The central limit theorem states that only if the shape of…

A random sample of n1 = 157 people ages 16 to 19 were taken from the island of Oahu, Hawaii, and 12 were found to be high school dropouts. Another random sample of n2 = 129 people ages 16 to 19 were taken from Sweetwater County, Wyoming, and 6 were found to be high school dropouts. Do these data indicate that the population proportion of high school dropouts on Oahu is different (either way) from that of Sweetwater County? Use a 1% level of significance. (a) What is the level of significance?   What is the value of the sample test statistic? (Test the difference p1 − p2. Do not use rounded values. Round your final answer to two decimal places.) (c) Find (or estimate) the P-value. (Round your answer to four decimal places.)

For several decades, it was a common practice in Southern California for houses to be built with pools in the backyard (as any airplane flight which ends at a Southern California airport will reveal). Now, however, that practice may be changing, possibly because of the recent demand for landscaped homes, which experts believe help reduce pollution. A recent study examined a random sample of  167  houses built in Southern California between 1950 and 1985 and an independent, random sample of  80  houses built in Southern California from 1992 to the present. The sample of houses built in 1950-1985 contained  71  houses with pools, and the sample of houses built from 1992-present contained  31  houses with pools. Based on this survey, can we conclude, at the  0.05  level of significance, that the proportion  p1  of all Southern California houses built in 1950-1985 that were built with pools is greater than the proportion  p2  of all Southern California houses built from…

The authors of a research article were interested in the effect on female viewers of watching movies in which female heroines were portrayed in roles that focus on their sex appeal. They carried out an experiment in which female college students were assigned at random to one of two experimental groups. The 24 women in one group watched 13 minutes of scenes from a certain superhero film series and then responded to a questionnaire designed to measure body esteem. Lower scores on this measure correspond to lower body satisfaction. The 29 women in the other group (the control group) did not watch any video prior to responding to the questionnaire measuring body esteem. For the women who watched the video, the mean body esteem score was 4.44 and the standard deviation was 1.02. For the women in the control group, the mean body esteem score was 5.07 and the standard deviation was 0.96. For purposes of this exercise, you may assume that the distribution of body esteem scores for each of the…

A researcher has access to 100 participants for an independent sample design study, and she is hoping to achieve power = .80.What effect size will her data need to achieve to make that possible?