PSYB04H3 Chapter Notes - Chapter 11: Measuring Instrument, Internal Validity, Spontaneous Remission
Document Summary
Threats to internal validity: did the independent variable really cause the difference? (3) common threats to internal validity are design confounds, selection effects and order effects. Design confounds experiment was poorly designed; another variable happened to vary systematically along with the intended independent variable. Selection effect different independent variable groups have different types of participants. Order effect outcome might be caused by the independent variable, but it also might be caused by the order in which the levels of the variable are presented. One-group, pretest/posttest design (the really bad experiement) a research 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. Instrumentation threat means the measuring instrument has changed from time 1 to time 2: a testing threat means the participant changes over time from having been. Three potential internal validity threats in any experiment tested before.
