week4 lab

    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

    1. 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
    2. 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.

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