DIGITAL PEDOMETERS

Abstract

More than a few studies are now underway using the pedometer as a research instrument. Typically a research instrument is calibrated to assure measurement accuracy before use. Because most digital pedometers cannot be adjusted (calibrated), the only option prior to use for research purposes is to check the calibration of each pedometer and remove an inaccurate instrument from service. In question is whether pedometers that have been used regularly maintain calibration. The purpose of this study was to check the calibration of pedometers using three different methods. Twenty-four digital pedometers were randomly selected from a pool of 240 (10%) that were being used in a longitudinal study. Ten of the 24 were relatively new and 14 had been used in previous research projects for one year. Each pedometer was tested in three different ways. Twenty-two participants (11 children and 11 adults) each wore all 24 pedometers. Actual walking counts were compared to counts on the pedometer for both child and adult participants. In addition a series of 11 shake tests were conducted for each of the 24 pedometers. Average differences in actual step counts (or shakes) and steps recorded on the pedometer were calculated for each pedometer. The average difference for all 24 pedometers was 3.60% for children, 2.26% for adults, and .39% for the shake test. Significant differences existed among all three groups (p < .001). None of the 24 pedometers had differences in steps counts of greater than 5% when pedometer actual counts were compared to counts by adults or when compared to the shake test. Two (8.3%) of the pedometers differed by more than 5% when assessed by children, most likely because of errors in counting by the participant. The results of this study suggest that digital pedometers, even those that have been in service for some time, provide accurate step count data. Still, it is recommended that a shake test and/or a step count check by adults be used to check calibration prior to use for research, and periodically during the course of long-term studies.