PSYC 2100WQ Chapter Notes - Chapter 11: Blind Experiment, Observer-Expectancy Effect, Demand Characteristics
15 Oct 2018
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A researcher recruits one group of participants, measures them on a pretest, exposes them to a treatment, intervention, or change, and then measures them on a posttest. A change in behavior that emerges more or less spontaneously over time. Alternative explanations which result from a historical or external factor that systematically affects most members of the treatment group at the same time as the treatment itself, making it unclear whether the change is caused by the treatment received. Refers to the statistical concept called regression to the mean. When a group average is unusually extreme at time 1 the next time that group is measured it is likely to be less extreme. A problem for internal validity when attrition is systematic, that is, when only a certain kind of participant drops out. An outside event or factor affects only those at one level of the independent variable. Only one of the experimental groups experiences attrition.
