Document Detail

Utility of global positioning system to measure active transport in urban areas.
MedLine Citation:
PMID:  17909415     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The purpose of this study was to determine test-retest reliability of global positioning system (GPS) units for measuring distance traveled when walking and cycling (AT), and to determine whether GPS unit placement influences accuracy. METHODS: Participants (N = 19) completed two walking and cycling trials at self-selected speeds on a measured 1489-m course wearing two Garmin GPS units, worn in lanyard and waistband placements. GPS estimates of travel distance were compared with actual distance, and test-retest reliability was examined. Data-cleaning protocols were developed to remove signal noise. Results are presented for both raw and cleaned data. RESULTS: For both raw and cleaned data, no significant differences were observed between trials (trial 1 vs trial 2), unit placement (lanyard vs waistband), or AT mode (walk vs cycle) (P >or= 0.05). Both lanyard and waistband units significantly overestimated distance traveled during walking trials (P <or= 0.05), but not cycling trials (P >or= 0.05). The relative technical error of measurement (TEM) of the raw data ranged from 3.74 to 15.51%, and average absolute errors ranged from 5.03 to 8.53% for all trials. A significant position by AT mode interaction was observed for clean data (P < 0.05). Relative TEM for the clean data ranged from 1.42 to 1.98%, and average absolute errors ranged from 0.32 to 1.97%. Intraclass correlations (ICC) were poor to fair for all trials using raw and cleaned data. CONCLUSION: Signal noise during unit initialization may adversely affect unit performance; however, application of data-cleaning procedures to remove data associated with signal noise improves unit ability to measure distance. Results suggest that the lanyard position is the optimal placement for units during data collection.
Mitch J Duncan; W Kerry Mummery; Ben J Dascombe
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Validation Studies    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  39     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-10-02     Completed Date:  2008-01-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1851-7     Citation Subset:  IM; S    
Centre for Social Science Research, Central Queensland University, Rockhampton, Australia.
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MeSH Terms
Geographic Information Systems / instrumentation*,  standards
Urban Population

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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