calculate_posterior function

Calculate posterior of ability

If the tauj is not within the range rello - relhi from the dynamic EAP, the procedure ignores the score of item j.

calculate_posterior(scores, tau, qp, scale, mu, sd, relhi, rello)

Arguments

• scores: A vector with PASS/FAIL observations. Scores are coded numerically as pass = 1 and fail = 0.
• tau: A vector containing the item difficulties for the item scores in scores estimated from the Rasch model in the preferred metric/scale.
• qp: Numeric vector of equally spaced quadrature points.
• scale: Scale expansion
• mu: Numeric scalar. The mean of the prior.
• sd: Numeric scalar. Standard deviation of the prior.
• relhi: Positive numeric scalar. Upper end of the relevance interval
• rello: Negative numeric scalar. Lower end of the relevance interval

Returns

A list with three elements:

Name	Label
eap	Mean of the posterior
gp	Vector of quadrature points
posterior	Vector with posterior distribution.

Since dscore V40.1 the function does not return the "start" element.

Author(s)

Stef van Buuren, Arjan Huizing, 2020