Agreement and Repeatability of a Time-Interval Measurement Prototype for Controlled Horizontal-Displacement Tasks

Abstract

The development of locally engineered technology for human movement assessment offers an alternative to costly imported instruments. This instrumental method-comparison study evaluated the repeatability of Prototype II, a photocell-based electronic device for measuring time intervals during controlled horizontal-displacement tasks, and its agreement with Newtest Powertimer and Chronojump Boscosystem in indoor and outdoor environments. Repeatability was assessed at 1.5, 6, and 15 s in sessions separated by 24 hours. Agreement was assessed at 2, 5, and 12 s using 35 paired technical repetitions for each interval-by-environment condition, with simultaneous measurements from Prototype II and both comparison systems. Relative reliability was summarized with ICC(2,1), while absolute repeatability was prioritized using CV% and SEM; agreement was summarized with Lin's CCC. ICCs for repeated Prototype II measurements were low or negative under restricted between-trial variance, whereas CV% ranged from 0.49% to 1.92% and SEM from 0.019 to 0.042 s. CCC ranged from 0.94 to 0.99 outdoors, from 0.809 to 0.915 indoors at 2 and 5 s, and from 0.623 to 0.636 at 12 s indoors. These results support repeatable technical performance and substantial agreement in several tested conditions, particularly outdoors, but do not establish practical interchangeability because no a priori acceptable-difference threshold was defined. Prototype II is a promising locally developed timing system that warrants further validation against traceable standards and during real movement tasks.