2. Suppose you are a researcher who is interested in the effects of diet and exercise on blood pressure levels of males and females age 30-40. How could you obtain blood pressure readings from your subjects?

3. Collect Data Analyze Data Report Results/Make Decisions Possible reasons for the observed results? Treatment was effective There were pre-existing differences between the groups. Poor instrumentation Treatment (or control) was not implemented correctly It was a fluke (e.g., chance)

4. Reliability: Does your measuring device produce consistent results? Validity: Does your measuring device produce accurate results? Instrument: A test or other tool that is used to collect data Instrumentation

5. Reliability is a necessary but not sufficient condition for validity

6. Types of Reliability Stability Equivalency Internal Consistency Interrater Interobserver Types of Validity ContentConstruct PredictiveConcurrent

7. Types of Reliability Stability Equivalency Internal Consistency Interrater Interobserver

8. Types of Validity ContentPredictive ConstructConcurrent

9. Characteristics of reliability and validity They are a matter of degree The estimates are specific to groups Validity is specific to the interpretation/context

10. Locating Existing Instruments Tests in Print Mental Measurements Yearbook Test Critiques