| "Unlike distance measurements, three-dimensional coordinate data has not had the benefit of close scrutiny. Thus, biases and sources of error in this type of data are not well known. Knowledge of error is critical to data reliability and plays directly into appropriate interpretation of results." - Corner, et al., 1992; Engineering anthropometry has adopted new technologies in the past three decades. Metrics of measurement reliability, however, are still based on traditional methodologies, created for traditional anthropometric techniques. This work analyzes the variability of three-dimensional anthropometric landmarks of the upper extremity under repeated measures and offers a new perspective on reliability data analysis for electromechanical anthropometry.; Variables that affect precision and corresponding spatial variation of three-dimensional anthropometric landmark digitizations are hypothesized in this work. The ability to explain spatial variation is an important step in understanding variability in human body measurement, as these landmarks are the origins of linear dimensions reported and used in a variety of ergonomic interventions. Spatial variations of three-dimensional landmark digitization data collected from three studies conducted at the University at Buffalo from 2002-2005 are analyzed. Knowing the digitization variability of a particular landmark can inform engineers and anthropometrists of the precision to which particular three-dimensional landmarks can be assessed. The rationale here is that understanding landmark digitization variance associated with three-dimensional landmark placement will have a cumulative effect on the precision and repeatability of structural and dynamic anthropometric data. Getting to the root of variability will allow for a greater understanding of the output data of three-dimensional anthropometry, which will aid in its use for design of workspaces, clearances, safety, and other human-environment interaction considerations. |
