normTable.betabinomial function

Calculate Cumulative Probabilities, Density, Percentiles, and Z-Scores for Beta-Binomial Distribution

This function generates a norm table for a specific ages based on the beta binomial regression model. In case a confidence coefficient (CI, default .9) and the reliability is specified, confidence intervals are computed for the true score estimates, including a correction for regression to the mean (Eid & Schmidt, 2012, p. 272).

normTable.betabinomial(
  model,
  ages,
  n = NULL,
  m = NULL,
  range = 3,
  CI = 0.9,
  reliability = NULL
)

Arguments

• model: The model, which was fitted using the optimized.model function.
• ages: A numeric vector of age points at which to make predictions.
• n: The number of items resp. the maximum score.
• m: An optional stop criterion in table generation. Positive integer lower than n.
• range: The range of the norm scores in standard deviations. Default is 3. Thus, scores in the range of +/- 3 standard deviations are considered.
• CI: confidence coefficient, ranging from 0 to 1, default .9
• reliability: coefficient, ranging between 0 to 1

Returns

A list of data frames with columns: x, Px, Pcum, Percentile, z, norm score and possibly confidence interval