Research Designs
Researchers were interested in learning the effects of trans fats on levels of cholesterol in the blood. Two different research designs were constructed.
Between-Groups Design
In the between-groups design, researchers were interested in whether cholesterol levels would differ depending on diet. Twenty participants were randomly
assigned to one of two different groups. Group A was assigned a diet rich in fruits and vegetables and with no trans fats. Group B participants were asked to
follow their normal diets, which contained varying levels of trans fats depending on the individual. After one month, blood samples were drawn and the
following levels of cholesterol were obtained:
Participant Blood Cholesterol Diet
1 129 Healthy
2 98 Healthy
3 150 Healthy
4 75 Healthy
5 135 Healthy
6 175 Healthy
7 115 Healthy
8 103 Healthy
9 156 Healthy
10 143 Healthy
11 239 Normal
12 500 Normal
13 350 Normal
14 468 Normal
15 198 Normal
16 213 Normal
17 225 Normal
18 175 Normal
19 560 Normal
20 289 Normal
Within-Subjects Design
In the within-subjects design, researchers were interested in whether participants could lower their cholesterol levels by changing from a diet higher in trans
fats to one with no trans fats. Ten research participants were selected. A baseline measure of cholesterol was taken from each. They were then put on a diet
rich in fruits and vegetables and devoid of trans fats for one month. At the end of that month, blood cholesterol was again measured, and the following
results were obtained:
Participant Blood Cholesterol Diet
1 129 Baseline
1 98 Healthy
2 150 Baseline
2 75 Healthy
3 175 Baseline
3 135 Healthy
4 115 Baseline
4 103 Healthy
5 156 Baseline
5 143 Healthy
6 500 Baseline
6 450 Healthy
7 468 Baseline
7 350 Healthy
8 198 Baseline
8 213 Healthy
9 225 Baseline
9 175 Healthy
10 560 Baseline
10 481 Healthy
In a Microsoft Word document, answer the following questions:
What is the independent variable in the study for a Between-Subject Design? What are the levels of that independent variable? What is the dependent variable?
What is the independent variable in the study for a Within-Subject Design? What are the levels of that independent variable? What is the dependent variable?
Name this document SU_PSY2008_W5_A_ LastName_FirstInitial
Based on what you learned in your lecture on Data Files for Between- and Within-Subject Designs , create a data file in Microsoft Excel that will enable you to
conduct a between-subject analysis of this data.
On a separate tab within your Microsoft Excel file (click the + sign at the bottom to create a new worksheet) create a data file that will enable you to conduct a within-subjects’ analysis of this data.
