A researcher would like to determine if relaxation training will affect the number of headaches for chronic headache sufferers. For a week prior to training, each participant records the number of headaches suffered. Participants then receive relaxation training and for the week following training the number of headaches is again measured. What test should you perform? Do the results indicate a significant difference? Use a two-tailed test with a = .05. and compute Cohen's d to measure the size of the effect.

A repeated measures study with n=26 participants produces a mean difference of M D = 3 points, SS=500 for the difference scores, and t=2.50. Calculate Cohen's d and r square (r2) to measure the effect size for this study.

Las Vegas has seen increased competition from Singapore and Macau for customers in the casino resort industry. One measurement of success is the average length of stay by visitors. The data in this file show the number of days a random sample of visitors stayed at each location. a. Using α = 0.05 to determine if there is a difference in the average length of stay by visitors for the three locations. Follow the steps as outlined in the exercises. b. If warranted, perform a multiple comparison test to determine which pairs are different using α = 0.05. c. Verify your results using Excel.

Suppose an experiment finds that people taking a new herbal remedy get fewer colds than people taking a placebo.  The results are statistically significant at the 0.01 level.  Has the experiment proven that the herbal remedy works?

(Please show all work on how you got this so I may learn from it and check my answers.) A researcher is interested in understanding if perfume affects how attractive a person is perceived tobe. To examine this phenomenon, the research randomly assigns the participants to rate theattractiveness of an individual from one of three groups: no perfume, a small amount of perfume, and alarge amount of perfume. Below are the ratings to how attractive the participants find the individual:NO Perfume      A SMALL Amount of Perfume             A LARGE Amount of Perfume4                        6                                                          05                        3                                                          13                        5                                                          05                        4                                                          14                        5                                                          23…

Denny studied factors affecting cardiovascular reactivity to a postural change in a sample of healthy men and women. Change in systolic blood pressure (SBP) from supine to standing position was used as the measure of cardiac reactivity in a sample of 842 adults. Supine measurement of blood pressure was taken after participants had lain on an examination table for 15 minutes. Blood pressure was determined every 30 seconds using a Dinamap device for 2 minutes, and the measurements were averaged. Participants then stood up immediately, and additional measurements were made for another 2 minutes. Below is a table describing the characteristics of Denny’s sample: Which measures of dispersion, if any, are presented in this table (Ranges, SDs)? If age is normally distributed, approximately what percent of the sample would be younger than 50? If BMI is normally distributed, approximately what percent of the sample would have a BMI higher than 33.1?

You are conducting a study to see if the proportion of women over 40 who regularly have mammograms is significantly different from 0.22. Your sample data produce the test statistic z = 3.03 . Find the pvalue accurate to 4 decimal places.