Validating stage of change measures for physical activity and dietary behaviors for overweight women.
OBJECTIVE
To investigate the construct, concurrent and predictive validity of stage of change measures for physical activity (PA), and intakes of fruit and vegetables (FVs), dietary fiber (FB) and dietary fat (DF) among a sample of overweight women.


METHODS
Subjects were 401 women (mean age=41, s.d.=8.7 years; mean body mass index=32.35, s.d.=4.6) recruited to participate in a 12-month weight loss intervention trial. Concurrent validity tests included (1) self-report of current behavior, (2) decisional balance (for example, pros and cons of behavior change), (3) self-efficacy, (4) the MTI Actigraph accelerometer (for the PA staging measure), and (5) a food-frequency questionnaire (for all dietary staging measures). Predictive validity was assessed through tests of the relationship between the baseline stage of change measures and their corresponding behavior 1-year later.


RESULTS
Coefficient alpha-tests of internal consistency exceeded 0.70 on the majority of scales. Concurrent validity tests indicated strong validity evidence for three staging measures and little validity for the DF staging measure (eta(2) range, 0.02-0.18). All staging algorithms demonstrated predictive validity (eta(2) range, 0.04-0.126).


CONCLUSIONS
Staging measures can determine motivational readiness for overweight women, contribute to the standardization of stage of change assessment and facilitate cross-study comparisons.
Robinson
A H
AH
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305-5722, USA. athenar@stanford.edu
Norman
G J
GJ
Sallis
J F
JF
Calfas
K J
KJ
Rock
C L
CL
Patrick
K
K
D000328:Adult; D000465:Algorithms; D016022:Case-Control Studies; D004038:Diet, Reducing; D004041:Dietary Fats / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D005247:Feeding Behavior; D005260:Female; D005638:Fruit; D006801:Humans; D008875:Middle Aged; D009042:Motivation; D009043:Motor Activity; D050177:Overweight; D011237:Predictive Value of Tests; D014675:Vegetables
D004041:Dietary Fats; D004043:Dietary Fiber