Title
Response conversion for improving comparability of international physical activity data
Author
Hopman-Rock, M.
Dusseldorp, E.
Chorus, A.
Jacobusse, G.
Ruetten, A.
van Buuren, S.
Publication year
2012
Abstract
Background: Many questionnaires for measuring physical activity (PA) exist. This complicates the comparison of outcomes. Methods: In 8 European countries, PA was measured in random samples of 600 persons, using the IPAQ as a 'bridge' to historical sets of country-specific questions. We assume that a unidimensional scale of PA ability exists on which items and respondents can be placed, irrespective of country, culture, background factors, or measurement instrument. Response Conversion (RC) based on Item Response Theory (IRT) was used to estimate such a common PA scale, to compare PA levels between countries, and to create a conversion key. Comparisons were made with Eurobarometer (IPAQ) data. Results: Appropriateness of IRT was supported by the existence of a strong first dimension established by principal component analysis. The IRT analysis resulted in 1 common PA scale with a reasonable fit and face validity. However, evidence for cultural bias (Differential Item Functioning, DIF) was found in all IPAQ items. This result made actual comparison between countries difficult. Conclusions: Response Conversion can improve comparability in the field of PA. RC needs common items that are culturally unbiased. Wide-scale use of RC awaits measures that are more culturally invariant (such as international accelerometer data). © 2012 Human Kinetics, Inc.
Subject
Human
CH - Child Health
BSS - Behavioural and Societal Sciences
Health
Healthy Living
Cultural bias
Differential item functioning
IPAQ
Item response theory
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http://resolver.tudelft.nl/uuid:5d7f0f46-a1a3-48cf-93b7-c6cc409b9198
TNO identifier
446411
ISSN
1543-3080
Source
Journal of Physical Activity and Health, 9 (1), 29-38
Document type
article