a)Each childs name was put into a computer, and using an online randomizer students were assigned to the experimental group or to the control group. At baseline, the food choice test was conducted. One day at school, research assistants showed each group their respective videos in separate classrooms. Because of some staffing issues, the experimental groups training was delivered by the same graduate student who ultimately coded all of the childrens food choices at lunch. Two days later, the food choice test was conducted. The mean score for children in the control group was 1.0 and the mean score for children in the experimental group was 3.5. We conclude that the 20-minute interactive video improved childrens food choices.

Answers: Between-subjects, post-test only , Within-subjects, post-test only , Between-subjects, pre-test-post-test One group, pre-test-post-test

hint:Each child is assigned to one condition (control or experimental). There is a baseline measurement, as well as a measurement after the manipulation.

b)Each childs name was put into a computer, and using an online randomizer students were assigned to the experimental group or to the control group. At baseline, the food choice test was conducted. One day at school, research assistants showed each group their respective videos in separate classrooms. Because of some staffing issues, the experimental groups training was delivered by the same graduate student who ultimately coded all of the childrens food choices at lunch. Two days later, the food choice test was conducted. The mean score for children in the control group was 1.0 and the mean score for children in the experimental group was 3.5. We conclude that the 20-minute interactive video improved childrens food choices.

Answers: Maturation History Regression to the mean Attrition Testing Instrumentation Observer bias Demand characteristics Placebo effect Confounding variable Selection effect Order effect No threat

hint:This study involves coding of behaviors. In this case, the research assistant doing the coding is not masked ("blind") to the condition that the children were place in. This means that expectations about the predicted pattern of results could have shaped the research assistant's coding.

c)Early in the school year, the food choice test was conducted as a baseline. The experimenter fell ill soon afterward, and so it wasnt until a class late in the school year that the children viewed the 20-minute interactive video (experimental condition). Two days after that, a second food choice test was conducted. The mean score for the children on the first food choice test was 1.2 and their mean score on the second food choice test was 3.4. We conclude that the 20-minute interactive video improved childrens food choices. Answers: Between-subjects, post-test only Within-subjects, post-test only Between-subjects, pre-test-post-test One group, pre-test-post-test

hint: There is only one condition (the experimental group). There is a baseline measurement, as well as a measurement after the treatment. This is an example of the "bad experiment" discussed in the lecture.