Three-Parameter Logistic Model

The Three-Parameter Logistic (3PL) Model is a mathematical way to understand how well a test question or item distinguishes between different levels of ability or trait. It considers three factors: how difficult the item is, how well it can differentiate between individuals of varying ability, and the chance of getting it right by guessing. This model helps test developers improve assessments by analyzing item performance, ensuring that each question accurately measures what it’s supposed to, and providing a more precise understanding of a person's ability based on their responses.