Following are the statements of Assertion (A) and Reason (R). Answer them with the help of the following codes:
Assertion (A): IRT is commonly used in computerized psychological testing to estimate ability.
Reason (R): In IRT, four parameters can be estimated.

Correct option is C

Assertion (A) is correct—IRT (Item Response Theory) is widely used in computerized adaptive testing to estimate ability. However, Reason (R) is false because IRT typically uses up to three parameters (difficulty, discrimination, guessing), not four.

Information Booster:
• IRT models the relationship between latent traits (like ability) and item responses, allowing ability estimation from test performance
• Computerized Adaptive Testing (CAT) uses IRT to select items matching the test-taker's ability level, providing efficient and precise measurement
• 1-Parameter Model (Rasch): Estimates only item difficulty
• 2-Parameter Model: Estimates difficulty and discrimination (how well an item differentiates ability levels)
• 3-Parameter Model: Adds pseudo-guessing parameter (probability of correct response by chance)
• IRT offers advantages over Classical Test Theory: item-free ability estimates, test-free item parameters, and precision information at all ability levels