Reliability and Concurrent Validity of the Metrecom for Length Measurements on Inanimate Objects

Background and Purpose. The purpose of this study was to test the reliability and concurrent validity of length measurements (distance between two points) produced by a computer-interfaced, three-dimensional digitizer called the Metrecom. Methods. A total of 344 points were marked on the surfaces of five different inanimate objects and were digitized in pairs with the Metrecom. On the first three objects, each of two testers digitized each point twice for each of two testing modes (Line Length and 3-D Digitizer); on the last two objects, only one mode (3-D Digitizer) was used. Intraclass correlation coefficients and Pearson Product-Moment Correlation Coefficients were used to assess reliability and concurrent validity, respectively. Results. All of the correlation coefficients were ≥.99. In further analysis of the results, a repeated-measures, one-way analysis of variance (used with reliability data) and repeated-measures t tests (used with validity data) were used to test for differences between repeated measures. After adjustment of the alpha level for the total number of comparisons, two of the t tests for validity comparisons were significant. Conclusion and Discussion. The results indicate that the Metrecom provides reliable length measurements (distance between two points) on inanimate objects and that two different test modes produce consistent measurements. Further study of the validity and reliability of length measurements obtained with the Metrecom on humans under applied conditions is needed before the results of this study can be generalized to applied settings.