At which difficulty level (pass proportion) the item can make highest differentiation?

Correct option is B

The correct answer is 0.50. The item can make the highest differentiation at a difficulty level (pass proportion) of 0.50. This refers to the point where an item has the greatest potential to discriminate between individuals who have different levels of ability. At a pass proportion of 0.50, half of the test-takers answer the question correctly, and half answer incorrectly, which maximizes the item’s ability to distinguish between individuals with varying abilities. This level of difficulty is ideal because the item is neither too easy nor too difficult, making it most effective at differentiating between the higher and lower-performing individuals.

Information Booster
-At a difficulty level of 0.50, the item provides the greatest opportunity for differentiation between test-takers.
-When the pass proportion is 0.50, there is a balanced distribution of correct and incorrect answers, which makes the item most effective in distinguishing between different levels of ability.
-Items with difficulty levels much lower (like 0.25) or higher (like 0.75) tend to be less effective at distinguishing because most individuals either answer them correctly or incorrectly, leaving little room for differentiation.
-Items at a 0.50 pass proportion are best suited for measuring the range of abilities within a group.
-The difficulty level of 0.50 is commonly used in test design to maximize the ability of individual items to differentiate between test-takers.
-This principle is used in item analysis and test construction to create fairer, more effective assessments.