Week 5

• Is the degree of truthfulness of a test score - The degree to which the test or instrument measures what it is supposed to measure

Relevance Reliability

Face validity Content validity

• Infers that a test is valid by definition - It is clear that the test measures what it is supposed to

• Infers that the test measures all aspects contributing to the variable of interest • e.g. who is the most physically fit

concurrent validity Predictive validity

• Infer that the test produces similar results to a previously validated test e.g. VO2 max

• Infers that the test provides a valid reflection of future performance using a similar test, e.g. can performance during test A be used to predict future performance in test B

Construct

• Infers not only that the test is measuring what is supposed to, but also that it is capable of detecting what should exist, theoretically • Therefore relates to hypothetical constructs

• Reliability relates to the consistency or repeatability of an observation • Degree to which repeated measures of the same trait are reproducible under the same conditions

Observed score true score error score

Observed score = true score + error score

Internal consistency reliability is a way to gauge how well a test or survey is actually measuring what you want it to measure.

It reflects the variation in measurements taken by an instrument on the same subject under the same conditions

The consistency of a given measurement from categorical outcomes

s a descriptive statistic that can be used when quantitative measurements are made on units that are organized into groups. It describes how strongly units in the same group resemble each other.

• Maturation • History • Statistical regression: An initial extreme score is likely to be followed by less extreme subsequent scores • Instrumentation e.g. Uncalibrated equipment • Selection Bias, e.g. Groups not randomly assigned

Hawthorne effect Demand characteristics

subject is influenced by the fact that it is being recorded, e.g. Fastest sprint when professor enters lab

Participants detect the purpose of the study and behave accordingly

Internal validity is the extent to which a piece of evidence supports a claim about cause and effect

External validity is the validity of applying the conclusions of a scientific study outside the context of that study