epm: Simulated dataset (Educational and Psychological Measurement, EPM)
Description
A simulated dataset, based on the the simRasch function. The data were generated on the basis of a 1PL IRT model with
50 items with a normal distribution and a mean difficulty of m = 0 and sd = 1 and 1400 cases. The age trajectory features a curve
linear increase wit a slight scissor effect. The sample consists of seven age groups with 200 cases each and it includes
information on the latent ability, the age specific latent ability and norm scores based on conventional norming with
differing granularity of the age brackets.
Usage
epm
Arguments
Format
A data frame with 1400 rows and 10 variables:
raw
the raw score
ageSpecificZ
the age specific latent ability, z standardized
latentTrait
the overall latent trait with respect to the population model
age
the chronological age
halfYearGroup
grouping variable based on six month age brackets
spcnT
Resulting norm score of cNORM, based on the automatic model selection
T1
conventional T scores on the basis of one month age brackets
T3
conventional T scores on the basis of three month age brackets
T6
conventional T scores on the basis of six month age brackets
T12
conventional T scores on the basis of one year age brackets
A data frame with 1400 rows and 10 columns
References
Lenhard, W. & Lenhard, A. (2020). Improvement of Norm Score Quality via Regression-Based Continuous Norming. Educational and Psychological Measurement. https://doi.org/10.1177/0013164420928457
if (FALSE) {
# Example with continuous age variabledata.epm <- prepareData(epm, raw=epm$raw, group=epm$halfYearGroup, age=epm$age)
model.epm <- bestModel(data.epm)
}