Introduction

Chapter 10
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You must read each slide, and complete any questions on the slide, in sequence.
Nonexperimental Design
A design in which there is no control or manipulation of the independent variable; cause-and-effect relationships between variables cannot be established.
Experimental Design
A research method in which the experimenter controls and manipulates the independent variable, allowing the establishment of cause-and-effect relationships between the independent and dependent variables.
Two-group Design
An experimental design that compares 2 groups or conditions and is the most basic way to establish cause and effect.
Pretest-posttest Design
A within-subjects design where participants are measured before and after exposure to a treatment or intervention.
Repeated-measures Design
A within-subjects design where participants are exposed to each level of the independent variable and are measured on the dependent variable after each level.
Independent Variable (IV)
The variable that influences the dependent variable. In experiments, the researcher manipulates or controls this variable.
Dependent Variable (DV)
The variable measured in association with changes in the independent variable; the outcome or effect.
Baseline Measurement
The initial assessment of a participant at the onset of a study, prior to any intervention or treatment.
Experimental Realism
The degree to which a study participant becomes engrossed in the manipulation and truly influenced by it.
Mundane Realism
The degree to which a study parallels everyday situations in the real world.
Reliability
The stability or consistency of a measure.
Validity
The degree to which a tool measures what it claims to measure.
Sensitivity
The range of data a researcher can gather from a particular instrument.
Order Effect
A threat to the interval validity in a within-subjects design resulting from influence that the sequence of experimental conditions can have on the dependent variable.
Practice Effect
Changes in a participant’s responses or behavior due to increased experience with the measurement instrument, not the variable under investigation.
Fatigue Effect
Deterioration in quality of measurements due to participants becoming tired, less attentive, or careless during the course of the study.
Carryover Effect
Exposure to earlier experimental conditions influencing responses to subsequent conditions.
Sensitization Effect
Continued exposure to experimental conditions in a within-subjects study increasing the likelihood of hypothesis-guessing, potentially influencing participants’ responses in later experimental conditions.
Counterbalancing
Identifying and using all potential treatment sequences in a within-subjects design.
Experimental Hypothesis
A clear and specific prediction of how the independent variable influences the dependent variable.
Institutional Review Board
A board that reviews the ethical merit of all the human research conducted within an institution.
Descriptive
Describes or summarizes what is happening in a meaningful way.
Inferential
Tests a specific prediction about why something occurs.

Within-Subjects Design

In this activity, you will explore the impact of inclusion and exclusion on self-esteem by creating a design to measure change within individuals.

Dr. Melanie Maggard

Dr. Natalie J. Ciarocco, Monmouth University

Dr. David B. Strohmetz, University of West Florida

Dr. Gary W. Lewandowski, Jr., Monmouth University

Something to Think About…

Scenario: Imagine that you are a child again. You are on the playground surrounded by your peers and it’s time for teams to be chosen for a game of kickball. Your hands start to sweat and your heart races as you think, Please let me get picked. Please let me get the chance to play today. You stand there attentively as the team leaders choose their players, but before you can be picked, they reach the number of players they want. You are devastated! As the teams run off to play, you think, Why didn’t I get picked? Do they not like me? What’s wrong with me?

Something to Think About…

Being excluded from social groups can cause us to reconsider how we feel about ourselves, even if these doubts are temporary. As social beings, we tend to feel better when we are part of a group, not excluded from one. Now, we are going to investigate this concept by exploring how several experiences of being included and excluded can impact self-esteem. Self-esteem affects the way we think, behave, and interact with others, so it is important to determine what factors might influence it.

Our Research Question

Based on experiences you may have with being included in or excluded from groups, you can develop a research study that examines the impact of social exclusion on self-esteem. First, you will need a framework to help you explore this topic. Research studies all start with a question, so here is your chance to ask one of your own.

Question 1.1

Which of the following research questions would be best to ask given the goal of our study?
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Picking the Best Design

Now that you have a research question (“Does being included in or excluded from playing a game with others impact young adults’ self-esteem?”), you must decide which type of research design will best answer your research question. To narrow things down, consider the following:

Question 1.2

Does your research question require a nonexperimental design or an experimental design?
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Picking the Best Design

Since comparisons must be made in order to answer your research question (“Does being included in or excluded from playing a game with others impact young adults’ self-esteem?”), consider the following types of experimental designs:

Question 1.3

Would your research question require a two-group, pretest-posttest, or repeated-measures design?
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Picking the Best Design

Having decided that your research question requires multiple measurements to determine impact, you must choose the best comparisons to make.

Question 1.4

Given the research question (“Does being included in or excluded from playing a game with others impact young adults’ self-esteem?”), which comparison is best?
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Picking the Best Design

Now that you know you have an experimental design that compares the pretest to inclusion in a game to exclusion from a game, you can identify your independent and dependent variables.

Question 1.5

Given the research question (“Does being included in or excluded from playing a game with others impact young adults’ self-esteem?”), what is your independent variable?
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Picking the Best Design

Question 1.6

Given the research question (“Does being included in or excluded from playing a game with others impact young adults’ self-esteem?”), what is your dependent variable?
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Picking the Best Design

Question 1.7

Because you have an experiment with 1 independent variable and 3 levels (Pretest vs. Inclusion in game vs. Exclusion from game) that each participant is exposed to, you will use a type of within-subjects design called a repeated-measures design. Why have we selected a within-subjects design to address our research question instead of a between-subjects design?
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Picking the Best Design

Your experiment includes 1 independent variable with 3 levels (Pretest vs. Inclusion in game vs. Exclusion from game). The pretest level serves as a baseline measurement to which the other measurements can be compared.

Question 1.8

Which of the following is an advantage of including a baseline measurement as the pretest in this study?
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Operationally Defining the Independent Variable

Next, we need to operationally define the independent variable (IV) of game condition by determining exactly how we will manipulate it. We will want to be sure that our study has a high level of experimental and mundane realism.

Question 1.9

Which of the following study options has the highest level of experimental and mundane realism?
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Operationally Defining the Independent Variable

It looks like the task that is highest in experimental and mundane realism involves young adults playing an electronic game of catch called “cyberball.” We know that all participants will be measured at 3 points in time: pretest (before the study begins), after being included in the game, and after being excluded from the game. Therefore, we will have the following design:

Summary of Our Within-Subjects Study
Pretest Measure IV Level 1 Time 1 Measure IV Level 2 Time 2 Measure
Self-esteem at Baseline Inclusion in Game Self-esteem after Inclusion Exclusion from Game Self-esteem after Exclusion

Operationally Defining the Dependent Variable

You have now established the key comparison between the Pretest vs. Inclusion in game vs. Exclusion from game. Next, we need to specify the exact nature of our dependent variable, self-esteem. First, consider the following:

Question 1.10

Which type of measure is better for assessing self-esteem?
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Choosing the Best Measure

We know we want to use a self-report measure to measure self-esteem. Now it is time to determine which type of self-report measure to use. Keep in mind how many and what types of questions, and what assessment of reliability, validity, and sensitivity, would be ideal for young adults.

Question 1.11

Which of the following would be the best self-report measure of self-esteem in this study?
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Choosing the Best Measure

We can update the chart we made earlier to reflect how we will be measuring the dependent variable, which is shown in the last row in the table below

Summary of Our Within-Subjects Study
Pretest Measure IV Level 1 Time 1 Measure IV Level 2 Time 2 Measure
Self-esteem at Baseline Inclusion in Game Self-esteem after Inclusion Exclusion from Game Self-esteem after Exclusion
SSES
at Baseline
SSES
after Inclusion
SSES
after Exclusion

Weighing Our Options

One potential problem with repeated-measures designs is the possibility of order effects.

The following are 4 types of order effects we could encounter in our study:

Question 1.12

Which of the following is not likely to be an order effect in this study?
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Weighing Our Options

Since we have the potential for multiple order effects in this study, we must consider how to minimize their impact. Fortunately, we do not think that the potential for practice and sensitization effects will drastically impact the results, so we decide to keep the same measure of self-esteem, SSES, constant throughout the study. However, we do think it would be worthwhile to reduce the impact of the carryover effect by using counterbalancing.

Question 1.13

Which of the following is the simpler way for us to use counterbalancing in our study?
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Weighing Our Options

Let’s update the chart we made earlier to reflect the counterbalancing method we have chosen for this study. Notice how we now have a second sequence that allows us to measure self-esteem after being excluded from a game and prior to exposure to the inclusion level, thus covering all possible sequences in our study.

Summary of Our Within-Subjects Study
Sequence Pretest Measure IV Level 1 Time 1 Measure IV Level 2 Time 2 Measure
#1 Self-esteem
at Baseline
Inclusion
in Game
Self-esteem
after Inclusion
Exclusion
from Game
Self-esteem
after Exclusion
SSES
at Baseline
SSES
after Inclusion
SSES
after Exclusion
#2 Self-esteem
at Baseline
Exclusion
from Game
Self-esteem
after Exclusion
Inclusion
in Game
Self-esteem
after Inclusion
SSES
at Baseline
SSES
after Exclusion
SSES
after Inclusion

Determining Your Hypothesis

Now that you have determined what you will manipulate and measure, you must formulate an experimental hypothesis.

Question 1.14

Which of the following is the best experimental hypothesis given the nature of your study?
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Finding a Sample

Before you can conduct your experiment, you need to determine exactly whom you want to study and where you can find this target sample.

Question 1.15

Which of the following samples would be best for your experiment?
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Submitting to the IRB

Now that you have determined how you will collect your data and your intended sample, you must submit your research procedure to the Institutional Review Board (IRB) for ethical approval. The IRB will determine whether or not your study meets all ethical guidelines.

  • (IRB)

Each IRB has its own protocol that conforms to the national standard when a researcher submits an application for proposed research. In addition to the appropriate paperwork and other information submitted to the IRB, the board would consider the following description during their evaluation of your proposed experiment:

  • The purpose of this research is to determine whether being included in or excluded from playing a virtual game of “cyberball” will result in a change to self-esteem. To study this topic, 30 participants will be randomly selected from the research participant pool at the University. Researchers will measure all participants’ self-esteem via the State Self-Esteem Scale (SSES) at the beginning of the study, after being included in a virtual game of “cyberball” for 5 minutes, and after being excluded from a virtual game of “cyberball” for 5 minutes. Counterbalancing will be used such that half of the participants will receive the inclusion-exclusion sequence and half will receive the exclusion-inclusion sequence. Participants will be debriefed at the end of the study.

Responding to the IRB

The IRB reviewed your submission and has one concern. Although the study appears to present less than minimal risk to participants, there is no mention of informed consent and voluntary participation.

You must now determine how to respond to the IRB, keeping in mind the ethics of respect for persons and autonomy.

Question 1.16

Which of the following is the best response to the IRB’s concern?
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Running the Study

chapter_10_multiple_choice

Now that we have secured the IRB’s approval, we should determine what the entire study will look like. Below are the steps of the study; can you place them in the proper order? (Note: The State Self-Esteem Scale is referred to as SSES.)

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Question

Slide 24

Collecting Data

Now that you have a sense of how to conduct this study, it is time to see what data from this study might look like.

If you were to run a full version of this study, you would want to have at least 30 participants. Because you have a within-subjects design, each participant will be exposed to all levels of the independent variable.

Example Data Set

This is an example of what your data set would look like. The top row shows the variable names; the other rows display the data for the first 5 participants in each sequence.

In the “Sequence” column, a 1 = Inclusion-Exclusion sequence, and a 2 = Exclusion-Inclusion sequence. The Baseline, Inclusion, and Exclusion columns represent a participant’s score measured via the SSES prior to the study, after inclusion in the game, and after exclusion from the game.

Participant Number Sequence Baseline Inclusion Exclusion
101 1 58 58 43
102 2 91 94 82
103 2 75 85 67
104 1 23 24 9
105 1 65 63 61
116 2 81 85 78
117 1 61 60 49
118 2 53 57 46
119 2 20 29 6
120 1 80 85 67

Selecting the Proper Tool

Now that you have collected your data, you must decide the best way to summarize your findings. The decisions you made about how to collect your data dictate the statistics you can use with your data now. First, you need to consider if your study is descriptive or inferential.

Question 1.17

Given the nature of your experiment, which of the following statistical methods is more appropriate?
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Tutorial: Evaluating Output

chapter_10_table_activity_1

The following is an example of output for another three-level design where participants experienced all 3 conditions in the study. This study was about how hours slept at night (6 hours, 8 hours, and 10 hours) influence self-reported happiness.

Before continuing, go through the tables to learn more about each of its elements.

Tests of Within-Subjects Effects
Measure: MEASURE_1
Source Type III Sum of Squares df Mean Square F Sig. Partial Eta Squared
Hours Sphericity Assumed 91.289

2

45.644

67.230

.000

.699

Greenhouse-Geisser 91.289 1.694 53.903 67.230 .000 .699
Huynh-Feldt 91.289 1.787 51.074 67.230 .000 .699
Lower-bound 91.289 1.000 91.289 67.230 .000 .699
Error(Hours) Sphericity Assumed 39.378

58

.679
Greenhouse-Geisser 39.378 49.113 .802
Huynh-Feldt 39.378 51.834 .760
Lower-bound 39.378 29.000 1.358

Question

Slide 28

Tutorial: Evaluating Output

chapter_10_table_activity_2

To report these numbers in a results section, enter the numbers as follows:

F from some variable equals a number; p equals a number; eta squared equals a number.

Pairwise Comparisons
Measure: MEASURE_1
(I) Hours (J) Hours Mean Difference (I-J) Sth. Error Sig. superscript b 95% Confidence Interval for Difference superscript b
Lower Bound Upper Bound
1 2

-2.200*

.222 .000 -2.762 -1.638
3

-.133

.164 .808 -.549 .283
2 1 2.200* .222 .000 1.638 2.762
3

2.067*

.244

.000

1.448 2.685
3 1 .133 .164 .808 -.283 .549

2

-2.067* .244 .000 -2.685 -1.448
Based on estimated marginal means
*. The mean difference is significant at the .05 level.
b. Adjustment for multiple comparisons: Sidak.

Question

Slide 29

Tutorial: Evaluating Output

chapter_10_table_activity_3
Descriptive Statistics
Mean Std. Deviation N
Six 1.77 .728 30
Eight 3.97 .809 30
Ten 1.77 .712 30

Question

Slide 30

Your Turn: Evaluating Output

Below is the output from your study:

Tests of Within-Subjects Effects
Measure: MEASURE_1
Source Type III Sum of Squares df Mean Square F Sig. Partial Eta Squared
GameCondition Sphericity Assumed 2081.156 2 1040.578 101.918 .000 .778
Greenhouse-Geisser 2081.156 1.816 1146.056 101.918 .000 .778
Huynh-Feldt 2081.156 1.930 2081.156 101.918 .000 .778
Lower-bound 2081.156 1.000 91.289 101.918 .000 .778
Error(GameCondition) Sphericity Assumed 592.178 58 10.210
Greenhouse-Geisser 592.178 52.662 11.245
Huynh-Feldt 592.178 55.983 10.578
Lower-bound 592.178 29.000 20.420

Your Turn: Evaluating Output

Below is the output from your study:

Pairwise Comparisons
Measure: MEASURE_1
(I) GameCondition (J) GameCondition Mean Difference (I-J) Std. Error Sig. superscript b 95% Confidence Interval for Difference superscript b
Lower Bound Upper Bound
1 2 -3.133* .728 .001 -4.979 -1.288
3 8.267* .788 .000 6.271 10.262
2 1 3.133* .728 .001 1.288 4.979
3 11.400* .944 .000 9.008 13.792
3 1 -8.267* .788 .000 -10.262 -6.271
2 -11.400* .944 .000 -13.792 -9.008
Based on estimated marginal means
*. The mean difference is significant at the .05 level.
b. Adjustment for multiple comparisons: Sidak.
Descriptive Statistics
Mean Sth. Deviation N
Baseline 61.10 25.694 30
Inclusion 64.23 24.694 30
Exclusion 52.83 26.478 30

Your Turn: Evaluating Output

chapter_10_multiple_choice_2

Based on the results of your statistical analyses, match the correct number in the “Answer” column to the term requested under “Prompt”:

Feedback

Question

Slide 23

Activity: Graphing Results

In order to visualize your data, use the values on the previous screens to input the mean that corresponds to each condition listed in the output. Then, check out the graphic representation of your data, below.

chapter_10_graph_activity
Descriptive Statistics
Mean Std. Deviation N
Baseline
25.694 30
Inclusion
24.694 30
Exclusion
26.478 30
Feedback

Question

Slide 34

Your Turn: Results

Now that you have worked with your data, you must determine the best way to express your findings in written form. You must be sure that how you describe your findings accurately represents the data.

Question 1.18

Based on the statistical analysis, which of the following results sections best fits the data and analyses from your study?
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Take Home Message

You have determined how to express your findings in a scientifically responsible way. Now, you need to be able to talk about what your findings mean in everyday terms so that the world can benefit from your science.

Question 1.19

How would you explain what you found about self-esteem in relation to inclusion in and exclusion from a game to a friend or family member? Select the best option.
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Congratulations! You have successfully completed this activity.


Slide 1. Introduction