LESSON 3: RELIABILITY

Reliability and Related Concepts

Reliability refers to the extent to which assessment results are consistent. The assessment that maintains the consistency in results is known as reliable.

“Reliability is the extent to which a measurement instrument or procedure yields the same results as on repeated trails (Carmines and Zeller, 1979)”

For example, a calculator cannot be reliable if it gives wrong calculations or results. The weight of an object is not reliable if machine is not working properly. Same is the case of the results obtained from assessments.

What is meant by the term of unreliable results? The unreliable results of assessment mean inconsistency. Keeping these views in mind, we can trust the results if these are consistent. It is the evidence of an accurate system of assessment. Keeping in view the significance of reliability, different methods are used to attain reliability. For example, test-retest procedure, the alternative–test form procedure and the split halves procedure.

Test-retest Procedure

Same test, given two (or more) times. Example: One might develop a test and will be administered twice with the same students. If the subject provides very small answers both times, it means results will be similar. Then one can assume that the assessment results are reliable.

Advantages of using ‘Test-Retest Procedure’:

  • This procedure has strong logical appeal, one is measuring more than once with the identical test.
  • One avoids the problem of developing more than one test.

Disadvantages of using ‘Test-Retest Procedure’:

  • Events taking place
  • Persons might change
  • Students become more practiced second time.

Alternative-test Form Procedure

Create two forms of the same test (vary the items slightly). Reliability is stated as correlation between scores of Test1 and test 2. If students give similar answers, it means the results will be the same and it will have reliability.

Advantages:

  • As tests differ though slightly, students cannot apply their guess work

Disadvantages:

  • One has to develop two tests.

Split Halves Procedure

  • Same test, administer once, grade each half separately, compare grades from each half.

Advantages

  • Need to develop just one test.
  • No maturation
  • No cueing

Disadvantages

  • What is the criterion of splitting halves?

Internal Consistency Procedure

  • Same test, administered once, score is based upon average similarity of responses to the items. It is a measure of reliability used to evaluate the degree to which different test items that probe the same construct produce similar results.

Advantages

  • Need to develop just one test.
  • No maturation.
  • No cueing.

Disadvantages

  • Scholars do not agree on the formula applied to calculate internal consistency.

Coefficients Range

  • The value of reliability coefficients range from 0 to 1.0.
  • A coefficient of 0 means no reliability.
  • 1.0 means perfect reliability but hard to claim.
  • If it is above .80, it is said to have good reliability; if it is below .50, it would not be considered a very reliable test.

Multiple Choice Questions (MCQs)

Reliability and Related Concepts

  1. What does reliability in assessments refer to?
  • A) The accuracy of results
  • B) The consistency of results
  • C) The difficulty of the test
  • D) The validity of the test
  • Answer: B) The consistency of results
  1. Which of the following best defines reliability according to Carmines and Zeller (1979)?
  • A) The accuracy of the measurement instrument
  • B) The extent to which a measurement instrument or procedure yields the same results on repeated trials
  • C) The relevance of the test content
  • D) The ease of administration of the test
  • Answer: B) The extent to which a measurement instrument or procedure yields the same results on repeated trials
  1. What does unreliable assessment results mean?
  • A) Accuracy
  • B) Consistency
  • C) Inconsistency
  • D) Reliability
  • Answer: C) Inconsistency
  1. Which method is NOT used to attain reliability?
  • A) Test-retest procedure
  • B) Alternative-test form procedure
  • C) Split halves procedure
  • D) Criterion-referenced procedure
  • Answer: D) Criterion-referenced procedure

Test-Retest Procedure

  1. What is the main advantage of the test-retest procedure?
  • A) Measuring more than once with the identical test
  • B) Developing multiple tests
  • C) Testing different groups of students
  • D) Ensuring test results are accurate
  • Answer: A) Measuring more than once with the identical test
  1. Which is a disadvantage of the test-retest procedure?
  • A) It requires developing two tests
  • B) Students become more practiced the second time
  • C) It measures the same concept twice
  • D) It uses different test items
  • Answer: B) Students become more practiced the second time

Alternative-Test Form Procedure

  1. What is an advantage of the alternative-test form procedure?
  • A) Students cannot apply guesswork
  • B) Only one test needs to be developed
  • C) It eliminates the need for scoring
  • D) It provides immediate results
  • Answer: A) Students cannot apply guesswork
  1. What is a disadvantage of the alternative-test form procedure?
  • A) It requires only one test
  • B) It eliminates maturation effects
  • C) Developing two tests is necessary
  • D) It is easier to administer
  • Answer: C) Developing two tests is necessary

Split Halves Procedure

  1. Which of the following is an advantage of the split halves procedure?
  • A) Need to develop just one test
  • B) Requires two test administrations
  • C) Involves maturation effects
  • D) Uses cueing techniques
  • Answer: A) Need to develop just one test
  1. What is a disadvantage of the split halves procedure?
    • A) No need for cueing
    • B) No maturation effects
    • C) Determining the criterion for splitting halves
    • D) Requires multiple test administrations
    • Answer: C) Determining the criterion for splitting halves

Internal Consistency Procedure

  1. What does the internal consistency procedure measure?
    • A) The reliability of different test items probing the same construct
    • B) The external validity of the test
    • C) The accuracy of test administration
    • D) The time taken to complete the test
    • Answer: A) The reliability of different test items probing the same construct
  2. What is a disadvantage of the internal consistency procedure?
    • A) Only one test is required
    • B) No maturation effects
    • C) Scholars disagree on the formula to calculate internal consistency
    • D) It requires cueing techniques
    • Answer: C) Scholars disagree on the formula to calculate internal consistency

Coefficients Range

  1. What does a reliability coefficient of 0 indicate?
    • A) No reliability
    • B) Perfect reliability
    • C) Good reliability
    • D) Moderate reliability
    • Answer: A) No reliability
  2. A reliability coefficient above 0.80 indicates what?
    • A) Poor reliability
    • B) Moderate reliability
    • C) Good reliability
    • D) Perfect reliability
    • Answer: C) Good reliability