PSYCO212 Lecture Notes - Lecture 25: Measuring Instrument, Construct Validity, Observer-Expectancy Effect

• School: University of Alberta
• Department: Psychology
• Course: PSYCO212
• Professor: Poliana Barbosa

Document Summary

Good researchers will creatively apply common design strategies to work around all common threats to internal validity and make strong causal statements. Three of the most common threats to internal validity are design confounds, selections effects, and order effects. It is important for an experiment to have a control group. One group, pre-test/post-test design: a study in which a researcher recruits one group of participant, and measures before and after the study. Maturation: a threat to internal validity that occurs when an observed in an experimental group could have emerged more or less spontaneously over time. History threat: a threat to internal validity that occurs when it is unclear whether a change in the treatment group is caused by the treatment or by a historical event that affects everyone of almost everyone in the group. Preventing history threat: add a comparison (control) group.