Learn Before
Basic Two-Group Experimental Design
In an ideal two-group experimental design, the only difference between the experimental and control groups is their exposure to the experimental manipulation. Both groups go through all phases of the study, but they experience different levels of the independent variable. The researcher then measures any changes produced in the dependent variable for each group and analyzes the collected data statistically to determine if there are meaningful differences between them.
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Ch.2 Psychological Research - Psychology @ OpenStax
Psychology @ OpenStax
Introduction to Psychology @ OpenStax Course
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OpenStax Psychology (2nd ed.) Textbook
Psychology
Social Science
Empirical Science
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Hypothesis
Independent Variable
Dependent Variable
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Basic Two-Group Experimental Design
Random Assignment
A researcher wants to test if a new public speaking workshop reduces anxiety. They measure the anxiety levels of 50 volunteers before they participate in the workshop. A week after the workshop is completed, the researcher measures their anxiety levels again and finds that the average anxiety level has decreased. The researcher concludes the workshop is effective. What is the most significant flaw in this study's design?
Operational Definition
Simple Random Sampling
Learn After
Control Group
Experimental Group
Example of a Two-Group Experiment: Technology in the Classroom
Logic of Causal Inference in Controlled Experiments
A researcher is conducting an experiment to determine if a new energy drink improves participants' performance on a complex puzzle. One group of participants drinks the new energy drink, while a second group drinks a similar-tasting beverage without the active ingredients. Both groups are then timed on how long it takes them to solve the same puzzle. For the researcher to validly conclude that the energy drink caused the observed difference in puzzle-solving times, which of the following is the most critical condition of the research design?
Factorial Design