RIM: A Random Item Mixture Model to Detect Differential Item Functioning

In this paper we present a new methodology for detecting differential item functioning (DIF). We introduce a DIF model, called the random item mixture (RIM), that is based on a Rasch model with random item difficulties (besides the common random person abilities). In addition, a mixture model is assumed for the item difficulties such that the items may belong to one of two classes: a DIF or a non-DIF class. The crucial difference between the DIF class and the non-DIF class is that the item difficulties in the DIF class may differ according to the observed person groups while they are equal across the person groups for the items from the non-DIF class. Statistical inference for the RIM is carried out in a Bayesian framework. The performance of the RIM is evaluated using a simulation study in which it is compared with traditional procedures, like the likelihood ratio test, the Mantel-Haenszel procedure and the standardized p -DIF procedure. In this comparison, the RIM performs better than the other methods. Finally, the usefulness of the model is also demonstrated on a real life data set.     

It Ain’t What You Say...

This essay takes as its starting-point the recent announcement that GCSE English, the high-stakes test taken by 16-year-olds in England, will no longer include the assessment of speaking and listening. It attempts to place this decision, and other recent policy interventions that will have an impact on how talk in the classroom is conceptualised and valued, in a longer history of schooling, attitudes to spoken English and the notion of a spoken standard. The essay then explores, through an account of an observed GCSE English lesson, something of the complexities involved in taking talk, and the assessment of talk, seriously.     

Disability as a Cultural Identity

Special education for disabled children is seen by many as being a major factor in the creation of a negative, second-class identity. This article suggests that disability is increasingly being seen as a positive cultural identity. Consequently, inclusive education has the potential to assimilate disabled children and subsume the promotion of disabled identity under the pervasive concept of diversity. Special schools could, therefore, under the control of disabled people become sites for the promotion of disability as a positive cultural identity and offer disabled children and their parents a genuine choice of education.