Does St. John wort (an herb) have a siginifact effect in treating major depression? A study looked at 340 adult outpatients suffering as measured by their HAM-Dscore, randomly assiging each subject to either a placebo, St.John's wort, or a second active treatment for comparison. The study found the diiference in treating major depression as measured by improvement in HAM-D scores between St.John's wort and the placebo was not statistically significant  This means that: A. a difference this big could easily occur just by chance even if St. John's wort does not better than the placebo B. We cannot make a 95 percent confidence statement C.The placebo makes no difference in the subjects' depression D. The study was badly designed

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?

You’re interested in knowing if a walking plus strength training exercise program results in a significantly greater increase in maxVo2 as compared to a walking only or a strength training only exercise program. Participants are randomly selected and then randomly assigned to one of three groups— walking plus strength training, walking only, or strength training only. After 6-months of exercise the participants are assessed. Which statistical analyses was used?

Q1: Placebo effect of exercise In a high-profile research study, Crum and Langer (2007) performed an experiment to test whether the relationship between physical exercise and health is impacted by one's mindset: in other words, if there is any "placebo effect" of exercise. A sample of 84 randomly selected hotel workers in the United States were placed either into a treatment group (n=44) or control group (n=40) depending on which hotel they worked at. The treatment group was given information demonstrating how their work is good physical exercise, while the control group was not given this information. They measured the body mass index (BMI) for each worker before the experiment and again four weeks after the experiment. a. Are the treatment group and control group independent of each other, and if so why? b. Now consider the treatment group alone: are the measurements of BMI taken before and after the experiment independent of each other, and if so why? c. What is the most appropriate…