Background: Case study research has been used increasingly in psychology and sociology in recent years. It provides researchers with an opportunity to explore a situation involving one individual or several individuals over time from multiple points of view. Methods: This literature review explains case study research as a method and summerises its scientific merit, also providing an example of its use. Results: Case study research offers occupational therapists a scientific methodology that can be used to understand and develop occupational therapy practice. Conclusion: This paper argues that case study research should be used more extensively by occupational therapists as the method respects the basic principles of occupational therapy. KEY WORDS case study research, occupational therapy research, qualitative research, research methodology.

The Play Assessment for Group Setting (PAGS) was constructed to measure children's play performance. The study was undertaken with 93 children aged from 2 to 8 years to examine whether the items of the PAGS construct a unidimensional scale that can be used to measure children's play ability. The internal scale validity and the person response validity of the PAGS were investigated by examining the goodness-of-fit of the play items and children's play performance to the many-faceted Rasch model for the PAGS. In total, 46 of the 51 play items demonstrated acceptable goodness-of-fit. Of the 93 children, 90.3% demonstrated acceptable goodness-of-fit on the scale of play items. Overall, the results support both the scale and person response validity for the PAGS, as well as providing preliminary evidence that the PAGS can be used for a more detailed evaluation of children's abilities in play performance within natural day-care contexts. Further research is needed to examine other aspects of the validity and reliability of the PAGS measures.

Play Assessment for Group Settings (PAGS) was originally designed to measure the play ability of 2- to 8-year-old children in their natural day-care context and for the use of different professionals. The main purpose of this study was to examine the inter-rater reliability of the PAGS. Twelve raters from different professional backgrounds scored a total of 78 children, both videotaped co-scored cases and individual live cases. The many-faceted Rasch model (MFR) was used to examine the goodness-of-fit of the rater severity estimates. Of the 12 raters, 91.7% were demonstrated to fit the MFR model expectations. Overall the results of this study indicated that the raters scored the PAGS in a reliable way, and that they behaved like independent experts. The separation index (2.09) of the raters indicated that the inter-rater scorings were comparable with each other for practical purposes. Further research on the different response processes of children in different diagnostic groups is needed.

We concluded that the PAGS is a valid tool for identifying children who have challenges in their play performance and can be used for clinical purposes. However, the slight variability supports the fact that differential item functioning should be controlled in research when using the PAGS for comparison of different subgroups in play performance.