Experimental Designs Show
The Uniqueness of Experimental Methodology Experimental Control Determination of Causality Internal versus External Validity Another advantage of a well-designed experimental method is its high level of internal validity. A design that has high internal validity allows you to conclude that a particular variable is the direct cause of a particular outcome. In contrast external validity is often seen as a challenge for experimental work. External validity is the degree to which conclusions drawn from a particular set of results can be generalized to other samples and situations. The sample in a particular experiment may not represent the larger population of interest, and the experimental situation may not resemble the real-world context that it is designed to model because of its artificiality. The concern around artificiality is controversial and not shared by everyone who does psychological research. Key Constructs of Experimental Methods Independent and Dependent Variables Experimental
and Control Groups Placebo Effect Random Assignment Types of Experimental Designs Between-Subjects Designs Advantages of Between-Subjects Designs Disadvantages of
Between-Subjects Designs Within-Subjects Designs Advantages of Within-Subjects Designs Disadvantages of Within-Subjects Designs Matched Group Designs Advantages of Matched Group Designs Disadvantages of Matched Group Designs Confounding Factors and Extraneous Variables Participant Characteristics The Hawthorne Effect Demand Characteristics Other Confounds Strategies for Dealing with Confounds Hold Potential Confounding Variables Constant Vary Test Items and Tasks Use Blind and Double-Blind Designs Statistically Control for Variables that Can’t be
Experimentally Controlled Use Randomization and Counterbalancing Ceiling and Floor
Effects What Steele and Aronson Found Ethical Considerations in Experimental Design Placebo/Control Group and Denial of Treatment Confederates and Deceit What is the term for when neither the researcher nor the participant is aware of what group they are assigned to?Listen to pronunciation. (DUH-bul-blind STUH-dee) A type of clinical trial in which neither the participants nor the researcher knows which treatment or intervention participants are receiving until the clinical trial is over.
What is the term for an experiment in which neither the participants nor the researchers know who is assigned to the experimental or control groups?A double-blind study is one in which neither the participants nor the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results.
During what kind of design are both the researcher and the participant unaware of what experimental condition they are in?In many experiments, either experimenters or participants are unaware of the experimental condition they are in. If only one of these groups, usually the participants, is “blind” to the intervention, then the study is said to have a single-blind design.
What is the type of experimental research design in which participants are not assigned randomly?Quasi-experimental research involves the manipulation of an independent variable without the random assignment of participants to conditions or orders of conditions.
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