1. DUMMIES RELIABILTY AND VALIDITY FOR By: Jeremy Starkey Lijia Zhang
November 4, 2002

2. RELIABILTY
Reliability is the consistency of measurement from one test to another.

3. PRECISION
Precision is defined as sharply or exactly defined; exact; particular.

4. VALIDITY
Validity is the appropriateness of the interpretations made from test scores (measurements) and other evaluation results.

5. ACCURACY
Accuracy is defined as done with care; exact; without error.

6. RELIABILITY Length of test Spread of scores Difficulty of test
Factors that influence reliability are:
Length of test
Spread of scores
Difficulty of test
Objectivity of test

7. RELIABILITY Longer the test, then usually the higher the reliability.
More questions on a test, then more reliable the test is.

8. RELIABILITY
Larger the spread of scores, then usually the higher the reliability.

9. RELIABILITY
Too easy or too hard tests results in low reliability because they restrict the spread of scores.

10. RELIABILITY
Multiple-choice questions are highly objective and can not be influenced by the scorer, thus should have a high reliability.

11. VALIDITY Factors that influence validity: unclear directions
reading vocabulary too difficult
ambiguity
inadequate time limits

12. VALIDITY Three categories for accumulating evidence of validity:
Content Validity
Criterion-related validity
Construct Validity

13. VALIDITY
Content Validity determines the extent to which a set of tasks provide both a relevant and representative sample of the domain of tasks about which the tests score are made.

14. VALIDITY
Criterion-related evidence is the extent to which test performance is related to some other valued measure of performance.

15. VALIDITY
Construct Validity interprets test performance in terms of some psychological quality.

16. RELIABILITY VS. VALIDITY
If low reliability, then you can not have high validity.
High reliability can either have high validity or low validity.
You must have reliability of some sort before you have validity.

17. PRECISION VS. ACCURACY
If you have poor precision, then you can not have good accuracy.
If you have great precision, then you can either have good or poor accuracy.
You must have some sort of precision before you can be accurate.

19. What a GREAT TARGET!!!!