Kiho Kim and Stevia Morawski (2012) reported the following in the abstract (brief summary) of their published research study: “Here, we report on the results of an experiment to evaluate the effects of tray availability on food waste production and dish use in a university dining facility. We sampled 360 individual diners over a 6-day period and documented a 32% reduction in food waste and a 27% reduction in dish use when trays were unavailable.”

a. What was the independent variable and what were its levels?

b. What were the dependent variables? How did the researchers likely operationalize their variables?

c. The researchers describe their study as an experiment. Explain what they mean by this.

d. Why would it be possible to use independentsamples t tests to analyze the data from their study?