Experimental Research

Keith Carrington

Valerie Nash

Keith Nerby

Kathleen Olewinski

Tanya Wojciechowicz

ED 740, November 2010

Experimental Research

Purpose: to test cause-and-effect relationships between variables

Experimental Research Groups

Experimental (Treatment) Group

“participates in an intervention” (p. 226)

experimented on or receives treatment

Control Group “a group that receives no intervention” (p. 226)

NOT experimented on and receives NO treatment

Leedy, P. D., & Ormrod, J. E. (2010). Practical research. Upper Saddle, NJ: Pearson Education.

Experimental Group: receives the treatment or is experimented on

Control Group: receives NO treatment; NOT experimented on

Group 1diet pill

Group 2 placebo

Group 1 Sustained Silent Reading

(SSR)

Group 2 Reading strategy

Experimental Group: receives the treatment or is experimented on

Control Group: receives NO treatment; NOT experimented on

Types of VariablesIndependent Variable

“variable that the researcher studies as a possible cause of something else -- in many cases, it is the one that the researcher directly manipulates” (p. 224)

The variable that is different or changed between groups. This is often the treatment or intervention.

Dependent Variable

“a variable that is potentially influenced by the independent variable… and so to some extent depends on the independent variable” (p. 224)

The variable that is measured or thought to be influenced by the independent variable.

Confounding Variable

Ways that two or more groups are or might be different in addition to the particular treatment or intervention.

When you have more than one independent variable.

Leedy, P. D., & Ormrod, J. E. (2010). Practical research. Upper Saddle, NJ: Pearson Education.

Independent variable: the item the researcher changed between the groups (often it is the treatment)

Dependent variable: variable thought to be influenced by the independent variable (is measured or observed)

Confounding variable: ways the groups might be different in addition to the independent variable

Group 1 diet pill

Group 2placebo

Group 1SSR

Group 2 Reading strategy

Independent variable: the item the researcher changed between the groups (often it is the treatment)

Dependent variable: variable thought to be influenced by the independent variable (is measured or observed)

Confounding variable: ways the groups might be different in addition to the independent variable

Controlling Confounding VariablesPurpose: to maximize internal validity by ruling out confounding variables

•Keep some things constant •Pretest to assess equivalence

•Include a control group •Expose participants to all experimental conditions

•Randomly assign people to groups

•Statistically control for confounding variables

Leedy, Table 10.1 (pp. 243-245)

Leedy, P. D., & Ormrod, J. E. (2010). Practical research. Upper Saddle, NJ: Pearson Education.

Types of Experimental Design1. Pre-Experimental Design: “forming a tentative hypothesis that should be followed up with more controlled studies” (p. 229)2. True Experimental Design: administering different treatments to a single group

3. Quasi-Experimental Design: considers the variables that researchers are unable to control and cannot rule out as alternative explanations for results

Leedy, P. D., & Ormrod, J. E. (2010). Practical research. Upper Saddle, NJ: Pearson Education.

Ex-Post-Facto Design“after the fact”

Purpose: to determine if causality exists

How: the researcher “studies the possible effect of an environmental factor that has occurred prior to the study itself” (p. 228)

Leedy, P. D., & Ormrod, J. E. (2010). Practical research. Upper Saddle, NJ: Pearson Education.

Meta-Analysis

Combines the results of several studies

Experimental Research Issues• Ethics and Integrity• Responsible Conduct• Informed Consent

(e.g., Harmon, 2010)http://www.nytimes.com/2010/04/25/

weekinreview/25harmon.html?_r=1• Human Subjects/

Research Participants• Conflict of Interest• Research Abuses• IRB Approval*• Publication/Peer Review• Collaborative Research

Cardinal Stritch University. (2010). Institutional review board. Retrieved from http://www.stritch.edu/irb.aspx

Experimental Research Collaborations

Benefits Challenges

Broadened experimental approach

Differences in approaches

Interdisciplinary; new knowledge formed

Responsibility and accountability

Development of new research strands

Ethical issues

Expertise, methodology and resources

Conflicts

Grants and other funding opportunities

Disclosing potential conflicts of interest

Heart Monitor ExperimentResearch Question: Do squat jumps change

instantaneous heart rate?

1. Establish and record your resting heart rate using the monitor.

2. If you are in the BLUE group, please remain seated without moving as much as possible. If you are in the ORANGE group, please do as many squat jumps as fast as possible in the time given.

3. Establish and record your heart

rate using the monitor.

Heart Monitor DataHeart Rate

Increased

Heart Rate

Decreased

Heart Rate

Stayed the Same

BlueGroupOrangeGroup

Please identify the following from the heart rate monitor activity.

1. Experimental Group - receives the treatment or is experimented on

2. Control Group - receives NO treatment; NOT experimented on

3. Independent variable - the item the researcher changed between the groups (often it is the treatment)

4. Dependent variable - variable thought to be influenced by the independent variable (is measured or observed)

5. Confounding variable - ways the groups might be different in addition to the independent variable

ReferencesCardinal Stritch University. (2010). Institutional review board.

Retrieved from http://www.stritch.edu/irb.aspx

Harmon, A. (2010, April 24). Where’d you go with my DNA? The

New York Times. Retrieved from http://www.nytimes.com/

2010/04/25/weekinreview/25harmon.html?_r=1

Leedy, P. D., & Ormrod, J. E. (2010). Practical research: Planning

and design (9th ed.). Upper Saddle River, NJ: Pearson

Education.