Comparative analysis of measurement discrepancy and reliability between direct and scanner-based methods in hand anthropometry

Background Accurate hand anthropometry underpins ergonomics, product design, medical applications, and occupational safety. Direct caliper-based measurement (DM) is labor-intensive and operator-dependent, whereas two-dimensional flatbed scanning (SC) has been advanced as a faster alternative, with validity for small anatomical landmarks remaining uncertain. Objective The objective of this study was to quantify between-method agreement and time efficiency of two-dimensional flatbed scanning (SC) relative to direct caliper measurement (DM). Methods In this study, 56 hand dimensions (36 lengths, 20 breadths) were obtained from 40 Thai adults (20 males, 20 females) by DM and SC. Between-method agreement were evaluated using mean absolute error (MAE), technical error of measurement (TEM), relative TEM (%TEM), and the coefficient of reliability (R). Time efficiency was quantified from average technician time and participant handling time. Results Pre-specified acceptability criteria (MAE ≤ 1 mm; TEM ≤ 2 cm; %TEM ≤ 1.5%; R ≥ 0.80) were satisfied by 42 of 56 dimensions (75%). Lengths and general breadths showed high agreement with the reference and strong repeatability (%TEM < 1.5%; R > 0.95), whereas small features—particularly finger-joint breadths < 25 mm—exhibited larger errors (%TEM 2.25–4.90%) and lower reliability (R < 0.80). Technician time was reduced from 30.85 to 14.10 min with SC, and participant handling was minimized (∼2.10 min). Conclusion Overall, SC can be adopted as a rapid, low-burden method for most hand dimensions, while refined protocols (e.g., increased image resolution, controlled hand pressure and posture, or equipment calibration) are indicated for sub-25-mm landmarks to ensure precision and strengthen population-specific anthropometric databases.