slides | Brandon LeBeau

Assessing the validity of item response theory models when calibrating field test items

April 9, 2016 slides, IRT, Field Test

Validity for IRT Models Validity is important for any assessment and the argument should begin with psychometrics. How the psychometrics is performed directly impacts properties of the assessment that are assessed later for evidence of validity. Are scores reported below chance level? The validity of the psychometrics is particularly important for field test data. IRT Model Field Testing Field testing (FT) is essential to new assessment development or form building.

Informative vs uninformative prior distributions with characteristic curve linking methods

April 8, 2016 slides, IRT, Linking

Linking overview With item response theory (IRT), the ability scale is arbitrarily defined (commonly mean of 0 and sd of 1). Linking is useful to help place individual ability and IRT item parameters on the same scale. Particularly when two forms are administered to non-equivalent groups. Four linking methods are common: Mean/Mean Mean/Sigma Haebara Stocking Lord Linking Transformation Linking Designs Random Groups Single group with counterbalancing Common-item nonequivalent group design More details in Kolen & Brennan (2014).

Interactively building test forms from an IRT perspective An application of R and Shiny

February 18, 2016 r, slides, shiny, buildform

Overview R R is an open source statistical programming language. Pros: Common statistical procedures are found in R Can extend functionality with packages/functions Cons: Need to be comfortable with code Reproducible Research Reproducible research has become popular. Commonly a document that contains both analysis and text. This can be done with Rmarkdown and knitr. Iterative/Interactive Data Analysis This type of analysis requires some input from the user.