1. Reliability and Validity

2. Validity
The extent to which an assessment tool actually measures what it is designed to measure
Ensures accurate conclusions can be made from the results

3. Types of Validity 1. Internal Validity 2. External Validity
CONTENT VALIDITY
CONSTRUCT VALIDITY
EXTERNAL VALIDITY
CRITERION RELATED VALIDITY

4. Face validity – WE ARE NOT GOING TO USE THIS
occurs where something appears to be valid. This is the least sophisticated measure of validity. Face validity is simply whether the test appears (at face value) to measure what it claims to.

5. Content validity
Content validity – are the instruments of research tools assessing what they are supposed to assess.
i.e. is an IQ test actually assessing general intelligence?

6. Construct validity
Construct validity – are the instruments or research tools effectively assessing Or all aspects of what we are measuring?
i.e. is an IQ test measuring all forms of intelligence?

7. External Validity
External validity – is the study done in such a way that findings can be applied to the wider population?
(i.e. if one 18yo benefitted from a learning technique, will all 18 yo benefit?)

8. Criterion related validity
– are the findings of the study consistent with other pieces of psychological research?
i.e. the study suggests that personality doesn’t change with age. Do other pieces of research agree?
How to improve VALIDITY:
Use a pacebo/control group.
Carry investigation out in realistic settings
Anything that will try eliminate bias/experimental effect.
Highly controlled environment.

9. Reliability
The extent to which an assessment tool measures what it is meant to measure consistently each time it is used

10. Types of reliability 1. Internal Reliability 2. External Reliability
INTERNAL CONSISTENCY RELIABILITY
TEST-RETEST RELIABILITY
PARALLEL FORMS RELIABILITY
INTER-RATER RELIABILITY

11. Internal consistency reliability
do all the items in the test contribute equally to what they are measuring. The degree to which a test measure the same variable to the same extent each time.
i.e. if you completed all the odd numbered questions, would you get the same score as if you completed all the even ones?

12. Test-retest reliability
Does the test produce the same results if the same person took it again at a different time? (Results should be the same)
i.e if they take the same IQ test twice, do they get the same score?

13. Parallel forms Reliability
Do two tests developed from the same content produce the same results?
i.e. do two IQ tests with different questions produce the same score?

14. Inter-rater Reliability
Are the same results achieved for the same participant when applied by different researchers?
eg: two researchers would both judge the participant to be equally depressed
How to improve RELIABILITY:
Test/restest. (i.e. repeating test).
Parallel forms.
Use previously researched testing methods.
Increase sample size.

15. QUIZ
Answer TRUE or FALSE to each of the following:

16. 1
Reliability is concerned with whether a test measures what it is supposed to measure on more than one occasion
TRUE

17. 2
Validity refers to whether or not the participant sample is representative of the population of interest
FALSE

18. 3
Internal consistency relates to whether a research study’s results are valid
FALSE – IC refers to whether all the items in a test contribute equally to the result

19. 4
If results of a study are reliable and valid they can be generalised to the population of interest
TRUE – if the sample is representative of the population

20. 5
A judgement about the meaningfulness of the results called a ___________________
Conclusion

21. 6
A _________________ can be made if the sample is representative of the population from which it came
Generalisation

22. 7
When a test measures the same variable to the same extent every time it has ________ reliability
INTERNAL / Test-Retest reliability