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ERIC Number: EJ870238
Record Type: Journal
Publication Date: 2009-Sep
Pages: 9
Abstractor: As Provided
Reference Count: 27
ISSN: ISSN-0270-1367
How Many Days Are Enough? A Study of 365 Days of Pedometer Monitoring
Kang, Minsoo; Bassett, David R.; Barreira, Tiago V.; Tudor-Locke, Catrine; Ainsworth, Barbara; Reis, Jared P.; Strath, Scott; Swartz, Ann
Research Quarterly for Exercise and Sport, v80 n3 p445-453 Sep 2009
This study was designed to determine the number of days of pedometer monitoring necessary to achieve reliable and valid estimates of a 1-year average of step counts in adults based on either consecutive days (CD) or random days (RD) of data collection. Twenty-three participants (16 women; M age = 38 years, SD = 9.9) wore a Yamax SW 200 pedometer and recorded their step counts for 365 consecutive days. Nine measurement periods of various lengths were selected (2, 3, 4, 5, 6, 7, 14, 21, and 30 days). Each measurement period was randomly selected 10 times each for CD and RD from the larger database. For reliability and validity, two-way intraclass correlation coefficients and mean absolute percentage error (MAPE) were calculated, respectively. The year-round average was considered the criterion measure of the "true" habitual physical activity. Data were analyzed separately by CD and RD. At least 5 CD or 6 RD were necessary to achieve an ICC of 0.80. A minimum of 30 CD or 14 RD were necessary to achieve an MAPE lower than 10%. These findings provide researchers and practitioners with useful information to determine appropriate measurement length and the method of data selection based on a desired level of reliability and validity. (Contains 3 tables and 4 figures.)
American Alliance for Health, Physical Education, Recreation and Dance. 1900 Association Drive, Reston, VA 20191. Tel: 800-213-7193; Fax: 703-476-9527; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: Practitioners; Researchers
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: South Carolina; Tennessee