Development of The Cognitive Estimation Test (BiTAHT) in healthy population and evaluation of reliability in individuals with multiple sclerosis

INTRODUCTION: Cognitive estimation is a component of executive functions, involving judgment, reasoning, often impaired in neurological disorders. This study aimed to develop the Bilişsel Tahmin Testi (BiTAHT) for the Turkish population and to evaluate its reliability and validity in patients with Multiple Sclerosis (pwMS). METHOD: The study was conducted in four sequential phases. In the first phase, 56 preliminary estimation items were generated based on a review of existing Cognitive Estimation Tests and expert feedback. In the second phase, the items were evaluated for clarity, linguistic appropriateness, and feasibility through pilot testing with a small sample. In the third phase, BiTAHT was administered to 1,112 healthy participants, and statistical analyses including percentile calculation and item-level outlier removal were used to refine the test and develop two parallel forms (BiTAHT-A and BiTAHT-B). In the final phase, reliability and validity were assessed by administering BiTAHT to 54 pwMS and 80 controls. The final version comprised six estimation categories: quantity, weight, length, duration, area, and equivalent. RESULTS: > .05). İnternal consistency was moderate when the two forms were combined. CONCLUSIONS: BiTAHT may be used to assess cognitive estimation abilities in Turkish adults and support future research on cultural validity. Although differences were observed between healthy controls and pwMS, these should not be interpreted as executive dysfunction. Future studies should evaluate test - retest reliability, expand validity evidence, and examine its utility in other neurological populations.