Validity Threats - Eppp Knowledge
- What is the internal validity threat when control participants change behavior because they are denied treatment?
- Compensatory rivalry (John Henry effect). Control group increases effort to compete with treated participants, altering outcomes.
- What internal validity threat occurs when dropout differs across groups and biases outcomes?
- Attrition (experimental mortality). Differential participant loss across conditions alters group comparability and results.
- What internal validity threat occurs when selection combines with maturation to create group differences?
- Selection × maturation interaction. Natural changes affect groups differently because of initial selection biases.
- Which internal validity threat best fits: a community disaster occurs between pretest and posttest?
- History. Unrelated external event influences participant responses between assessments.
- What is the external validity threat when results depend on when the study was conducted (historical period)?
- Interaction of history and treatment. Temporal context affects results, limiting generalizability to other historical periods.
- What internal validity threat occurs when selection combines with instrumentation to bias group comparisons?
- Selection × instrumentation interaction. Measurement inconsistencies affect groups differently due to selection effects.
- What is the internal validity threat when participants alter responses to appear favorable or acceptable?
- Social desirability (response bias). Participants provide answers they believe are socially acceptable, distorting true data.
- What is the internal validity threat when groups receive additional, unintended interventions besides the IV?
- Diffusion or imitation of treatments. Unintended spread of intervention elements to control groups blurs treatment distinctions.
- What internal validity threat occurs when selection combines with testing to create group differences?
- Selection × testing interaction. Pretest influences vary across groups owing to baseline selection disparities.
- What is the internal validity threat when control participants reduce effort because they expect to do poorly?
- Resentful demoralization. Control participants decrease performance due to perceived inequity and discouragement.
- What is the internal validity threat in which extreme scores move toward the mean on retesting?
- Regression to the mean. Statistical tendency for extreme values to approach the average upon repeated measurement.
- What is the internal validity threat when groups differ at baseline due to nonrandom assignment?
- Selection bias (selection effects). Non-equivalent groups at outset due to assignment methods confound treatment effects.
- What is the internal validity threat when staff give extra help to controls because they feel sorry for them?
- Compensatory equalization of treatments. Administrators provide unintended benefits to controls, contaminating group differences.
- What is the internal validity threat when participants change due to awareness of being observed in a study?
- Reactivity (Hawthorne effect). Participants modify behavior simply because they know they are under observation.
- Which internal validity threat best fits: a new rater is trained mid-study and scores shift upward?
- Instrumentation. Change in raters introduces inconsistencies in scoring, confounding measurement reliability.
- What is the internal validity threat caused by changes in measurement tools or observers over time?
- Instrumentation. Inconsistencies arise from alterations in measurement devices or observer criteria over time.
- Which internal validity threat is most likely if a study enrolls only clients with extremely high symptom scores?
- Regression to the mean. Selecting extremes leads to natural statistical regression toward average scores on retest.
- What is the internal validity threat when researcher expectations influence participant behavior or ratings?
- Experimenter expectancy effect. Researcher's biases subtly cue participants, influencing behavior or data interpretation.
- What is the internal validity threat caused by taking a pretest that alters later performance?
- Testing (pretest sensitization). Exposure to initial assessment sensitizes participants, influencing subsequent performance.
- What is the internal validity threat in which outside events occur between pretest and posttest?
- History. External events unrelated to the intervention confound changes between measurements.
- What is the internal validity threat in which participants change naturally over time (for example, fatigue)?
- Maturation. Natural developmental or physiological changes in participants occur independently of the treatment.
- What is the external validity threat when results depend on the specific setting or context of the study?
- Interaction of setting and treatment. Outcomes are limited to the particular environment, reducing applicability elsewhere.
- What is the external validity threat when results depend on the specific participants sampled?
- Interaction of selection and treatment. Treatment effects may not generalize beyond the unique characteristics of the sample.
- What internal validity threat occurs when selection combines with history to create group differences?
- Selection × history interaction. External events impact groups unequally due to pre-existing selection differences.
- What is the external validity threat when a pretest makes the treatment more effective than it would be otherwise?
- Interaction of testing and treatment. Pretesting alters participant responsiveness, making effects unrepresentative without it.