Dixon et al. (1987) undertook an experiment to see if information provision would effect dietary choices.
1. The hypothesis was that students given lessons on nutritious snacks will purchase healthier snacks from the canteen.
2. The design was to use a control group to compare and measure differences in the dependent variable before and after application of a stimulus. The experimental group would have a lesson on nutritious snacks. The control group would simultaneously have a lesson on another topic. The dependent variable (that is, student consumption of nutritious snacks) would be measured before and after the lessons given to the control group and the experimental group.
3. The control variables were age, gender and course of study.
4. The experimental and control groups were selected so that they were similar in age, proportion of males to females and course of study.
5. The dependent variable was measured by asking students to indicate, on a check list, which snacks they had bought from the canteen. The researchers backed this up by also observing what the students bought. The independent variable was whether or not the student had attended the lesson on nutritious snacks.
6. The experimental group was given the lesson on nutritious snacks while the control group had a lesson on something else.
7. The types of snacks purchased after the lesson were ascertained.
8. The two groups of students are as alike as possible in all known respects and the only known difference is the attendance or non-attendance at the lectures on nutritious snacks. Thus any difference between the two groups in what snacks they chose (the dependent variable) can be assumed to be caused by the lessons on nutritious snacks (the independent variable). The results showed no significant difference between the two groups.
9. The experimenters concluded that the lesson on nutritious snacks had no effect on the selection of snacks.