CAS PS 326 Study Guide - Final Guide: Concurrent Validity, Operational Definition, Nonprobability Sampling
2 Jul 2020
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Variables - measurement scales (nominal, ordinal interval ratio) Nominal : lowest level of measurement; only grouping. Ordinal : has an element of classification/ranking but also (democrat vs republican). has magnitude (letter grades). Interval : has classification + order + equal interval. Ratio : can"t go below a certain level (age, distance, hours). (temperature, sat scores). Variables can be either - the hypothesis should specify which you consider the variable to be. Survey/correlational research (what is it and main limitation) Cross sectional : measures everything at the same time. Longitudinal : tracking the same variables and people over time. More internal validity and better time order , but can"t eliminate 3rd variable explanations. Attrition: loss of participants over time people who drop out tend to have similar characteristics. Power: ability to detect significant effects or findings, so larger sample = more power. Successive independent samples design : series of cross-sectional studies over time measures different people.
