I recently noticed a new approach so called 'Rasch Analysis' when I worked on a paper in dealing with the MCID (minimal clinically important difference). I have not got chance to do any Rasch analysis on my own, but I have collected some information here for the future use.
Rasch analysis start to be used in education, survey area. In clinical trial, it is mostly used in psycometric, neurology areas where the outcome assessment relies on the instrument which typically contains certain number of items. These instruments are frequently used in CNS and neurology disease such as stroke, alzheimer, dementia. Traditionally, a scale or instrument will need to be validated through the reliability and validity tests. Recently, in addition to the reliability and validity tests, the Rasch measurement model has set new quality standards for outcome measures by appraising a broad range of measurement properties. You will not be surprised to see many papers if you user the search keyword "Rasch analysis" or "Rasch model" in Pubmed.gov.
There is no existing procedure within SAS to perform the Rasch analysis. However, there are some SAS macros for Rasch analysis on the internet developed by Karl Bang Christensen. The most popular software for Rasch analysis is Winsteps which provide a free download of a Ministep with capability of performing Rasch analysis for less items and less records.
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