Question

For the following scenarios below:

Identify the design as pretest-posttest, posttest only, repeated measures, or concurrent measures

Draw a sketch of the study’s results, using a bar graph or line graph.

Identify the threats to internal validity in each design, if any exist.

1. Due to time constraints, the experiment was run over four consecutive days. On day one, children viewed the 20-minute cartoon (control condition). On day two, the food choice test was conducted (it was a special “pizza day” in the cafeteria). On day three, the children were exposed to the 20-minute interactive video (experimental condition). Finally, on day four, a second food choice test was conducted. (It was a normal day in the cafeteria.) The mean score for children on the first food choice test was 1.0 and their mean score on the second food choice test was 3.5. We conclude that the 20-minute interactive video improved children’s food choices.

2. Each child’s name was put into a computer, and using an online randomizer students were assigned to the experimental group and to the control group. One day at school, research assistants showed each group their respective videos in separate classrooms. 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 children’s food choices.

3. Each child’s name was put into a computer, and using an online randomizer student were assigned to the experimental group and to the control group. During a class early in the school year, a food choice test was conducted for all children. The experimenter fell ill soon afterward, and so it wasn’t until a class late in the school year that children in the comparison groups were separated, with the control group children viewing the 20-minute cartoon and the experimental group children viewing the 20-minute interactive video. Two days after that, a second 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 children’s food choices.

4. It so happened that there was an equal number of boys and girls in the grade-one classrooms, so for convenience, the boys were assigned to the control group and the girls to the experimental group. One day at school, research assistants showed each group their respective videos in separate classrooms. 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 children’s food choices.

Answer 1

1. This is a repeated measures study.

The biggest threat to internal validity in this study is testing. It is possible that the participants' responses may have been impacted by order effects, with practice or fatigue impacting the results.

Please post the other questions separately. As per the answering guidelines we are supposed to answer just one question or four sub parts of the same question.