2.17. What is needed? Explain any flaws in each of the following proposed experiments and describe how you would improve the experiment. (a) Two product promotion offers are to be compared. The first, which offers two items for $2, will be used in a store on Friday. The second, which offers three items for $3, will be used in the same store on Saturday. (b) A study compares two marketing campaigns to encourage individuals to eat more fruits and vegetables. The first campaign is launched in Florida at the same time that the second campaign is launched in Minnesota. (c) You want to evaluate the effectiveness of a new investment strategy. You try the strategy for one year and evaluate the performance of the strategy.

Exercise is known to produce positive psychological effects. Interestingly, not all exercise is equally effective. It turns out that exercising in a natural environment (e.g., jogging in the woods) produces better psychological outcomes than exercising in urban environments or in homes (Mackay & Neill, 2010). Suppose that a sports psychologist is interested in testing whether there is a difference between exercise in nature and exercise in the lab with respect to post-exercise anxiety levels. The researcher recruits n 5 7 participants who exercise in the lab and exercise on a nature trail. The data below represent the anxiety scores that were measured after each exercise session.   Treat the data as if the scores are from an independent-measures study using two separate samples, each with n 5 7 participants. Compute the pooled variance, the estimated standard error for the mean difference, and the independent-measures t statistic. Using a 5 .05, is there a significant difference…

7. Effect size - Cohen's d and r squared An industrial/organizational psychologist has been consulting with a company that runs weekend job-seeking workshops for the unemployed. She collected data on several issues related to these workshops and, after conducting statistical tests, obtained statistically significant findings. She needs to find a way to evaluate effect size so that she can make recommendations to the company. One of the psychologist’s findings is that 18 months after the workshop, a sample of 36 job seekers who received training on resume writing scored an average of 7.3 as measured on a 9-point job-search motivation scale, with a standard deviation of 1.5. The typical job seeker scores 6.1 points. The psychologist finds that the estimated Cohen’s d is    , the t statistic is 4.80, and r² is    .   Using Cohen’s d and Cohen’s guidelines for interpreting the effect size with the estimated Cohen’s d, there is a    treatment effect. Using r² and the extension…

3. Scenario It is believed that large doses of acetaminophen (the active ingredient in over the counter pain relievers like Tylenol) may cause damage to the liver in nearly half of those tested. A researcher wants to conduct a study to estimate if the proportion of acetaminophen users who have liver damage is the same as previously reported. For participating in this study, he will pay each subject $20 and provide a free medical consultation if the patient has liver damage. Part A If he wants to limit the margin of error of his 98% confidence interval to 2%, what is the minimum number of subjects he needs?  (answer should be in the form of x,xxx) the minimum amount of money he needs to set aside to pay his subjects? $  (answer should be in the form of $xx,xxx) Part B The amount you calculated in Part A is substantially over his budget so he decides to use fewer subjects. Will this change increase or decrease the width of his confidence interval?  Will this new confidence interval be…