In the light of the above statements, choose the most appropriate answer from the options given below:

Given below are two statements: one is labeled as Assertion (A) and the other as Reason (R).
    Assertion (A): One psychometrician used Cronbach’s alpha to verify the reliability of a general knowledge test with answers in True/False format.
    Reason (R): Cronbach’s alpha estimates the internal consistency of a test.

Correct option is D

Why is (A) Incorrect?
        - Cronbach’s alpha measures internal consistency reliability, which applies best to continuous-scale items (e.g., Likert scale) rather than dichotomous (True/False) items.
        - For dichotomous items, a better measure of reliability is the Kuder-Richardson Formula 20 (KR-20).
        - Cronbach’s alpha can still be used for True/False tests but is not the best choice.

Why is (R) Correct?
        - Cronbach’s alpha is a widely accepted measure of internal consistency, which assesses how closely related a set of test items are.
        - A higher Cronbach’s alpha value indicates greater reliability.

Thus, while (R) is correct, (A) is incorrect, making Option (4) the correct answer.

Information Booster:

Cronbach’s Alpha (α):
    Measures internal consistency for tests with continuous responses (e.g., Likert-scale items).
    Formula 

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    Where K = number of items, σ²_i = variance of individual items, σ²_t = total variance.

Kuder-Richardson Formula 20 (KR-20):​
    Specifically designed for dichotomous (True/False, Yes/No) items.​
    More appropriate than Cronbach’s alpha for tests with binary scoring.

Types of Reliability Measures:
    Test-Retest Reliability: Stability over time.
    Inter-Rater Reliability: Agreement between different raters.
    Split-Half Reliability: Measures test consistency by splitting into two halves.
    Internal Consistency Reliability: Measured using Cronbach’s alpha or KR-20/KR-21.

Applications in Psychology & Education:
    Used in psychometric testing, personality assessments, and survey validation.
    Ensures questionnaires and psychological tests are reliable.

Limitations of Cronbach’s Alpha:
    Assumes unidimensionality (all items measure a single construct).
    Influenced by the number of test items (longer tests tend to have higher alpha values).