Question

The authors of the paper "Fudging the Numbers: Distributing Chocolate Influences Student Evaluations of an Undergraduate Course"† carried out a study to see if events unrelated to an undergraduate course could affect student evaluations. Students enrolled in statistics courses taught by the same instructor participated in the study. All students attended the same lectures and one of six discussion sections that met once a week. At the end of the course, the researchers chose three of the discussion sections to be the "chocolate group." Students in these three sections were offered chocolate prior to having them fill out course evaluations. Students in the other three sections were not offered chocolate. The researchers concluded that "Overall, students offered chocolate gave more positive evaluations than students not offered chocolate." Indicate whether the study is an observational study or an experiment. Give a brief explanation for your choice.

Answer 1

The study is an experimental study – not an observational one. This is clear from how the research methodology is explained in the question. An observational study would not have a manipulated variable – while manipulation of a variable (usually independent variable) is crucial for experimental research.

The manipulated variable in the research study is the chocolate offer, with two possible treatments – given chocolate, or not given chocolate. Based on the conducted research it is clear that the group of students who were offered chocolate gave more positive evaluations for the course than the group of students who weren’t offered chocolate.