| Definition | Term |
| Group to generalize to | Population |
| Subset of the population. | Sample |
| the fact researcher is interested in explaining | Dependant Variable |
| variable used to explain the one dependent or causally prior to dependent variable. | Independent Variable |
| When experimenter can intentionally create variation in independent variable (ie. amount of funding) | Manipulation |
| Rival explanations for behavior of dependent variable. | Confounding Variable |
| units observations are made (regions, municipalities, etc) | Subjects |
| Set of data with which treatment group is compared. | Control |
| Subjects have equal chance of being assigned to treatment group or control group-purely by chance. | Randomization |
| Program rather than other factor caused results. | Internal Validity |
| Can the effect be expected under similar conditions in other settings. | External Validity |
| Convenience sampling-those accessible; volunteer sampling - volunteers-OK for descriptive results, may be bias, not representative of population | non-probability sampling |
| Individual has equal chance of being selected for sample | Simple random (probability sampling) |
| every Xth individual selected form list, starting randomly chosen point | Systematic (probability sampling) |
| Population may have 2 or more groups in study-provides best results; ensures even coverage of population; maintains random selection probabilities. | Stratified (probability sampling) |
| Used when stratified or simple random sampling would be difficult and/or expensive. | Cluster (probability sampling) |
| As ______increases, standard error decreases | Sample size |