Investigating psychometric properties of the arm activity measure \u2013 Thai version (ArmA-TH) sub\u2010scales using the Rasch model

Montana Buntragulpoontawee,Stephen Ashford,Jeeranan Khunachiva,Tinakon Wongpakaran,Atcharee Kaewma,Patreeya Euawongyarti,Nahathai Wongpakaran

doi:10.1186/s12874-021-01238-5

Abstract

BackgroundThis study investigated the ArmA-TH sub-scale measurement properties based on item response theory using the Rasch model.MethodsPatients with upper limb hemiplegia resulting from cerebrovascular and other brain disorders were asked to complete the ArmA-TH questionnaire. Rasch analysis was performed to test how well the ArmA-TH passive and active function sub-scales fit the Rasch model by investigating unidimensionality, response category functioning, reliability of person and item, and differential item functioning (DIF) for age, sex, and education.ResultsParticipants had stroke or other acquired brain injury (n = 185), and the majority were men (126, 68.1 %), with a mean age of 55 (SD 22). Most patients (91, 49.2 %) had graduated from elementary/primary school. For the ArmA-TH passive function scale, all items had acceptable fit statistics. The scale’s unidimensionality and local independence were supported. The reliability was acceptable. A disordered threshold was found for five items, and none indicated DIF. For the ArmA-TH active function scale, one item was misfit and three were locally dependent. The reliability was good. No items showed DIF. All items had disordered thresholds, and the data fitted the Rasch model better after rescoring.ConclusionsBoth sub-scales of ArmA-TH fitted the Rasch model and were valid and reliable. The disordered thresholds should be further investigated.

Highlights

This study investigated the Arm Activity Measure questionnaire (ArmA)-TH sub-scale measurement properties based on item response theory using the Rasch model
As there has never been an objective self-report measure for assessing hemiparetic upper limb function for patients in Thailand, ArmA was translated into the Thai language as Arm Activity Measure Thai version (ArmA-TH) with a preliminary evaluation of psychometric properties, including a content validity index for both item (I-CVI) and score (S-CVI), interrater reliability, and internal consistency [3]
Neither the construct validity of the items nor a detailed item evaluation of ArmA-TH based on measurement theory were initially explored

Summary

Introduction

This study investigated the ArmA-TH sub-scale measurement properties based on item response theory using the Rasch model. According to Rasch measurement theory, an outcome measure scale should demonstrate unidimensionality (all items contribute to the same construct) and have no DIF (invariance across a sub-population) [4]. All these properties can be evaluated by conformity to the Rasch model, which the original English version of the ArmA passive function sub-scale was evaluated against in a UK sample [5]

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Discussion

Conclusion