Rind, B., & Strohmetz, D. (1999). Effect on restaurant tipping of a helpful message written on the back of customers’ checks. Journal of Applied Psychology, 29, 139-144. doi:10.1111/j.15591816.1999.tb01378.x This is the article to use to answer these questions 1. What are the design elements (IV, DV) and operational definitions? 2. What are the potential confounds? 3. What are the strengths and weaknesses of the study design? 4. The message written on the back of the check concerned an upcoming special dinner at the restaurant. Is it possible that it was the content of the message rather than simply a personalized message from the server that accounts for the results? How might the authors have evaluated this possibility? 5. Researchers used index cards to randomly assign the dining parties to the experimental and control conditions. What other strategies could they have used for random assignment in this field experiment? 6. Why did the researchers instruct the server to behave in the same way when delivering the check at the end of the meal? What possible threats to internal validity might be created if the server’s behavior varied when delivering the check? 7. How might the following aspects of this study limit the study’s external validity? A young female adult was the authors’ accomplice. The study was conducted at a private country club. The meal was buffet style.