1. Reliability and Validity

2. What does it mean?
In pairs, think of how we use the words reliability and validity in everyday life.
What do these words mean? Is there a difference between them or do they mean the same thing?

3. Reliability
When assessing the reliability of a study, we generally need to ask two questions
Can the study be replicated?
If so, will the results be consistent?
High vs low reliability

4. Measuring Reliability
Match the method of estimating reliability to the description (pg165)
Test-Retest reliability
If the measure depends upon interpretation of behaviour, we can compare the results from two or more raters.
If the results in the two halves are similar, we can assume the test is reliable
Split Half Reliability
Splitting a test into two halves, and comparing the scores in both halves
If the results on the two tests are similar, we can assume the test is reliable
Inter-Rater reliability
The measure is administered to the same group of people twice
If there is high agreement between the raters, the measure is reliable

5. Validity Control Realism Generalisability Realism vs Control
Did the IV cause the DV?
Realism
Does the experiment reflect real life?
Mundane realism
Generalisability
Can we generalise our results to the general population?
Realism vs Control

6. Types of Validity Internal validity External Validity
What happens inside the study.
External Validity
How our results can be generalised beyond the study
Validity of psychological measures
How well our methods of measurement actually measure what we intend

7. Internal Validity Mundane realism Extraneous variables Task A and B
Situational variables
Participant variables
Investigator effects
Demand characteristics
Participant effects
Task A and B
Name the variables
What are the EVs and how could they have been controlled?

8. External Validity
Read pg and fill in the gaps

9. Validity of psychological measures
Operationalisation of variables
Can result in loss of validity

10. Validity of psychological measures
Content validity
Does the method used actually seem to measure what you intended?
Concurrent validity
How well does the measure agree with existing measures?
Construct validity
Is the method actually measuring all parts of what we are aiming to test?
Predictive validity
Is our measure associated with future behaviour?

11. Validity of psychological measures
Complete tacks C, D and E.