Parameter Estimates

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Multivariate Methods • Item Analysis • The Item Analysis Report • Parameter Estimates

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The Parameter Estimates report contains a table of estimated parameters for each item. The parameters provided depend on the model used in your analysis (1PL, 2PL, or 3PL).

Item

The test item.

Difficulty

The b parameter or the measure of the difficulty of the item. A histogram of the difficulty parameters is shown beside the difficulty estimates.

Discrimination

(Available only for 2PL and 3PL models.) The a parameter or the measure of the item discrimination. A histogram of the discrimination parameters is shown beside the discrimination estimates.

Lower Asymptote

(Available only for 3PL models.) The c parameter or a measure of guessing.

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Help created on 10/11/2018