1. RELIABILITY & VALIDITY
What is Reliability?
How Can We Measure Reliability?
What is Validity?
What are the Types of Validity?

2. What is Reliability? Extent to which a measurement is consistent
There is always measurement error when measuring variables.
Larger measurement error means lower reliability.

3. Ways of Measuring Reliability
Inter-rater Reliability
Test-Retest Reliability
Alternate Forms Reliability
Split-Half Reliability

4. What is Validity?
Extent to which a method measures what it is claimed to measure
Reliability is a prerequisite for validity

5. Content Validity
Extent to which an instrument includes appropriate content
Consult experts about content of test

6. Construct Validity
Extent to which the appropriate construct is measured
Look for agreement with accepted measures of the same construct
Review literature to determine appropriate variables that represent the construct

7. Criterion Validity Extent to which behaviors are accurately predicted
Concurrent validity – present performance
Predictive validity – future performance
Use correlational research to determine and improve ability to predict

8. External Validity Extent to which the results can be generalized
Improve ecological validity – how well the method represents appropriate situations/settings

9. Internal Validity
Extent to which the results represent the relationship of interest
Eliminate or control confounding variables - extraneous variables that change systematically with a variable of interest