Kaz's SAS, HLM, and Rasch Model Rasch Model
 Home Large National Data Sets Kaz Library SAS manuals What is "error"? Rasch Model HLM SAS PROC NLMIXED and GLIMMIX Factor Analysis Reading output via SAS Excel functions for Statistical Analysis Essays on learning statistics Statistics in Japanese My profile My SAS questions and SAS's responses My work tool box
Please also visit my current note site kuekawa.com .
Rasch model is one of the psychometric models.  It helps us create measures.  The most famous application of Rasch model can be found in large education data sets, such as TIMSS and NELS, in the forms of student academic achievement scores.  Rasch model can also create attitudinal scales, such as student engagement level or liking of math.  We all need to be aware that Rasch model can get us good scales only when we design test items and surveys carefully.
 My way of Understanding Rasch Model 3 minute Rasch explanation to someone who at least knows what OLS regression is.  My Rasch Essay--I show how you may also experience "aha" moment if you see how Rasch model is related to logistic regression or HLM (actually HGLM or multilevel logistic regresssion). My Rasch Essay 2: Why Rasch model people don't agree with other models. See POWERPOINT presentation file (123k), almost the same as above file. why perfect data (a person getting all answers correctly or all wrongly) doesn't produce valid estimates and he proposes a solution.  He wrote, " I looked into the questions you raised using the attached Excel file to reanalyze John's data in your Appendix 1.  I conclude that some statistical information and a multiplication factor Beta are needed to solve the problem within the logit model framework.  All are described in the attachment.  The general logit model does have such a multiplication factor." Understanding outfit and infit statistics My memo (word document) One way to strengthen your understanding of Rasch model: Study a residual file from Winsteps (by specifying xfile=filename) and try to confirm how each column of information is derived (and understand how each variable in this file is interrelated).  Read sample winstep file sample pfile (person file) Excel Simulation 1: I simulated the construction of infitstatistics (Mortiz' version of Excel simulation *below* is easier to understand.  I think we used slightly different approaches.) Excel Simulation 2: Infit and outfit revisited Understanding Simulating Rasch model using SAS PROC LOGISTIC Click this photo to visit his winstep website