Rasch keyforms can help interpret clinical assessment scores. The Action Research Arm Test (ARAT) is a commonly used assessment, yet no keyform currently exists. The aim is to provide a keyform for the ARAT and demonstrate how a clinician can use the keyform to design optimally challenging rehabilitation sessions. Secondary analysis of ARAT data ( n = 122) using confirmatory factor and Rasch analyses were used to examine the measurement properties and generate a keyform. The item standardized factor loadings were >0.40 (range = 0.82-0.96) and R2 values were >.60 (range = .65-.96). All items exhibited adequate infit statistics with point measure correlations >.60 (range = .72-.97). Person reliability was .98, and person separation was 7.07. Item-difficulty measures ranged from -2.78 logits to 2.64 logits. The ARAT has strong measurement properties, and a keyform was provided. We showed how the keyform can be utilized by clinicians to interpret scores, set goals, and plan treatment.
Keywords: Rasch analysis; assessment; rehabilitation; stroke; upper extremity.