1. Define reliability. Discuss any two methods of estimating reliability of test scores.

• Reliability refers to the consistency of measurement. It indicates that any significant results must be repeatable.
• Two methods are:
  • Test-retest reliability: Repeating the same test on the same sample at two different time periods.
  • Parallel forms reliability: Comparing two equivalent forms of a test that measure the same attribute.

2. What is meant by internal consistency reliability? Discuss any two methods of assessing internal consistency reliability.

• Internal consistency refers to the extent to which items measuring the same phenomena produce similar results.
• Two methods:
  • Split-half reliability: Randomly dividing items into two sets and correlating the scores from each half.
  • Kuder-Richardson estimate of reliability: Using a formula to calculate reliability based on item difficulty.

3. What are some problems associated with reliability assessed via the test-retest method?

• Problems include:
  • Practice effects: Repeated tests may lead to improved scores.
  • Memory effect: Respondents may recall their previous answers.
  • Absence: People may be absent for re-tests.

4. State the strengths and drawbacks of parallel forms reliability.

• Strengths: It avoids the memory effect, and the practice effect.
• Drawbacks: It can be difficult to create truly equivalent forms of a test, and may be costly and time consuming to administer two forms.

5. Write short notes on: K-R formula 20, Spearman Brown formula, Cronbach alpha.

• Kuder-Richardson formula 20: A method for estimating internal consistency for tests where items are scored as 0 or 1.
• Spearman-Brown formula: Used to adjust split-half reliability, enabling correlation as if each part were a full length test.
• Cronbach's alpha: An index of reliability, considered the mean of all possible split-half coefficients.

6. Define validity and distinguish between reliability and validity.

• Validity refers to the degree to which a test measures what it claims to measure.
• Reliability is about consistency, while validity is about accuracy. A test can be reliable without being valid, but not valid without being reliable.

7. Explain construct validity. How does it differ from content validity?

• Construct validity measures the extent to which a test measures a theoretical construct.
• Content validity assesses if a test covers the range of behaviors represented by the theoretical concept being tested.

8. What is internal validity? Discuss various threats of internal validity.

• Internal validity concerns the logic of the cause-and-effect relationship between independent and dependent variables.
• Threats to internal validity include: events outside the lab, maturation, testing effects, regression effects, selection, and mortality.

9. What is external validity? Discuss various threats of external validity.

• External validity concerns the generalizability of research results to other situations, subjects, settings, and times.
• Threats to external validity include issues generalizing to different subjects, times, or settings.

10. Write short notes on: Convergent and divergent validity, Concurrent and predictive validity.

1. Convergent validity: The extent to which a measure correlates with other measures that it is theoretically predicted to correlate with.
2. Discriminant validity: The extent to which a measure does not correlate with measures that it should not correlate with.
3. Concurrent validity: A type of criterion-related validity where the criterion measures are obtained at the same time as the test scores.
4. Predictive validity: A type of criterion-related validity where the criterion measures are obtained after the test.

Important Points

1. Internal Consistency Concerns whether the various items on a test are measure the same thing.
2. Memory effect / carry over effect is not possible in parallel form method.
3. K.R. Formula is applied in which each test item is scored 0 or 1.
4. Scores from the two halves of a test are correlated with one another in split half reliability.
5. Spearman Brown formula is used for adjusting split half correlation.
6. If a test measures what it purports to measure it is called Validity
7. If a test is correlated against a criterion to be made available at the present time it is a type of validity known as Criterion validity.
8. The property of a test that measurement actually measure the constructs they are design to measure are known as Construct validity
9. A test should sample the range of behaviour represented by the theoretical concept being tested, is known as Content validity.
10. Face Validity refers to what appears to measure superficially.
11. Results can be generalised to another situation or population in external Validity.
12. Dropping out of some subjects before an experiment is completed causing a threat to internal validity.
13. Any bias in selecting the groups can decrease the internal validity.
14. Internal Validity concern the logic of relationship between the independent variable and dependent variable.
15. Confounding error occurs when the effects of two variable in an experiment can not be separated.