used to determine the relationship between variables when:
1. Manipulating the variables would be difficult or impossible.2. Manipulating the variables would be unethical.
A research technique which satisfies the following criteria:
1. Random assignment
2. Researcher manipulates the independent variable
Occur when the participant changes his or her behavior because he or she identifies the manipulations in the study.
1. Identity: occurs when different entities receive different scores
2. Magnitude: occurs when the ordering of the values reflects the ordering of the trait being measured
3. Equal Intervals: occurs when a difference of 1 on the scale means the same amount everywhere on the scale
4. Absolute Zero: occurs when a score of 0 indicates complete absence of the trait being measured
between sub design comparing means, 1 IV, 2 levels
Research designs in which each subject is assigned to one level of the independent variable.
Research designs in which subjects receives all independent variable levels
Few extreme low scores
-Fewer subjects; same number of observations
-Greater statistical power
occurs when different entities receive different scores.
this occurs when the ordering of values on the scale represents the ordering of the trait being measured
Correlation between IV levels (within only)
Variability in DV
-IV levels maximizing the effect size
-Lowering variability in the DV
-Increase sample size
the logic of experimentation breaks down if you have a confound because it could either be the confound or the IV responsible for the change in the DV
Mean is more affected by extreme scores
Method of counterbalancing. Assigns treatment orders in grid. (solves practice effects)