In a study on sodium-restricted diets, the researchers observed 50 patients with hypertension.  Among these, 22 were on sodium-restricted diets.  Of 200 patients without hypertension, 54 were on sodium-restricted diets. The researchers were curious to find out whether they can conclude that, in the sampled population, the proportion of patients on sodium-restricted diets is higher among patients with hypertension (p1) than among patients without hypertension (p2). Use a significance level of α = 0.05 for the test. The output of the analysis is given below.   Z Test for Two Proportions     Hypertension No hypertension   Sample Proportion xxx xxx   Number of Observations 50 200   Ho: xxx Ha: xxx     Z* xxx     P[Z > Z*] XXXXX     Z Critical, a = 0.05 1.644854                 1. Assume the calculated test statistic turns out to be 3.54. Then, the conclusion is that we should reject Ho. 2. What is the null hypothesis

A researcher was interested in how the effects of stress were different in people with our without military training.  A equal number of participants were recruited that either had no military experience or had completed military experience.  All participants were asked to give a speech without preparation while being judged by a panel of experts.  Their heart rates were monitored during the speech and an average heart rate was calcuated for each participant. Which statistical test would be best to determine if there is a significant difference between groups?     one-sample t-test     dependent samples t-test     independent samples t-test     ANOVA

A 1-1 matched case-control study was conducted among office workers on the association between suffering chronic lower back pain and sitting at a PC. There were 118 cases (suffering from back pain), individually matched to controls (not suffering from back pain) on sex, age, and general exercise habits. The exposure was the amount of time spent at a PC. The data are in Table 1: Case > 4 hours/day 4 hours/day 18 13 <4 hours/day 25 62 Use a suitable test to test for no association between suffering chronic lower back pain and time spent sitting at a PC.

You also conducted a review of the research literature and found that similar studies examining the relationship between alcohol consumption and liver cancer found the following: Smithson et al. RR 3.3 (95% CI:1.95-5.20)  Ribera et al. RR 2.1 (95% CI:1.17-3.33)  Gonzalez et al. RR 2.75 (95% CI 2.26-3.45) Which one of Hill’s criteria does this illustrate? Explain.

The Wall Street Journal asked Concur Technologies, Inc., an expense management company, to examine data from 8.3 million expense reports to provide insights regarding business travel expenses. Their analysis of the data showed that New York was the most expensive city. The following table shows the average daily hotel room rate (X) and the average amount spent on entertainment (Y) for a random sample of 9 of the 25 most-visited U.S. cities. These data lead to the estimated regression equation y = 17.49 + 1.0334x. For these data SSE = 1541.4. Use Table 1 of Appendix B.  a. Predict the amount spent on entertainment for a particular city that has a daily room rate of $89 (to 2 decimals). b. Develop a 95% confidence interval for the mean amount spent on entertainment for all cities that have a daily room rate of $89 (to 2 decimals). c. The average room rate in Chicago is $128. Develop a 95% prediction interval for the amount spent on entertainment in Chicago (to 2 decimals).

Many people take ginkgo supplements advertised to improve memory. Are these over-thecounter supplements effective? In a study, elderly adults were assigned to the treatment group or control group. The 104 participants who were assigned to the treatment group took 40 mg of ginkgo 3 times a day for 6 weeks. The 115 participants assigned to the control group took a placebo pill 3 times a day for 6 weeks. At the end of 6 weeks, the Wechsler Memory Scale was administered. Higher scores indicate better memory function. Summary values are given in thefollowing table:                N               x              sGinkgo 104           5.7         0.6Placebo 115         5.5          0.5a) Based on these results, is there evidence that taking 40mg of ginkgo 3 times a day is effective in increasing mean performance on the Wechsler Memory Scale? b) Write a brief report on your findings

A study was conducted to explore the possibility of a audiobook treatment effect on sleep quality (better, worse). One version of the study involved 32 uber drivers. The uber drivers were given the option to choose which group they were in. One group listened to an audiobook while they slept, while the other group did not. The researchers found a difference of 21.9 percentage points between the proportion of uber drivers in each group who experienced better sleep quality. The group that listened to an audiobook had the higher proportion. The tail proportion from a randomisation test carried out with the data from the study was 1/1000.