methods
Maturation
- Research development changes and/ or learning that occurs and may be confound with
IV
Testing effects
- testing procedure and/or practice effects may be confounded with IV
Regression toward the mean
-may occur whenever 2 measurements are imperfectly related; extreme values
from first measurement are generally with associated less extreme values
Selection/ experimenter bias
- process of selecting participants may lead to bias
Mortality
- some participants may be less likely to complete a study resulting in bias
Good subject tendency
- altering of behavior to comply with expectations about task demands
Statistical validity