Theory of Planned Behavior

ARTICLE REVIEW

EVAN HILBERG

Article Review A Test of the Theory of Planned Behavior to Explain Physical Activity in a Large Population Sample of Adolescents from Alberta, Canada

Journal of Adolescent Health, 2011

Plotnikoff, Lubans, Costigan, et.al.

Theory of Planned Behavior Social-cognitive theory used to explain PA behaviors

A person’s intention to perform a behavior is the central determinant

Intention determined by attitude, social norms, and perceived control

Attitude-

Norms-

Perceived control-

Introduction/Purpose TBP hasn’t been tested extensively in adolescent populations

Primary objective-◦ Explore the power of TBP to explain PA behaviors in adolescents

Alternative objectives-◦ Explore moderating effects of gender◦ Explore mediating effects of intention

Methodology Validated, short measures of TBP constructs (att, norms, intent)

Attitude- 2 item construct (enjoyment and importance)

Subjective Norms- “Most people important to me think I should take part in regular PA”

Methodology

Intention- “I plan to be physically active on a regular basis over the next month”

Perceived behavior control- 4 item self-efficacy measure

Validated PAQ for Older Children used to assess PA levels over 7 days

Methodology Series of models used to test secondary objectives

◦ Gender was ID as a potential moderator◦ Unrestricted to fully constrained models◦ Intention seen as mediator

Analysis of moment structures used to test primary objective◦ Adjusted for school

Results Sample reflects overall Alberta population

The model testing revealed an excellent fit to the data◦ All pathways significant◦ Model explained 59% and 43% (intention/behavior)

Mediation analyses◦ Intention found to mediate relationship between variables and PA◦ All pathways were significant

Results Moderation analyses revealed excellent fit to the data

◦ Both boys and girls◦ Further analyses showed stronger relationship among boys in model◦ Also showed stronger relationship among boys among pathways

Plotnikoff et al’s test of TPB

Discussion Largest TPB study in youth with a representative sample

Results support the TPB with significance for all construct pathways

Perceived control and intention accounted for 43% of variance of behavior

Attitude, norms, and perceived control explained 59% of the variance for intention

Discussion Results are consistent with other literature in adult and adolescent populations

Differences existed between genders in the models

Perceived control was strongest correlate of behavior for all

Attitude was strongest correlate of intention for all

Discussion Mediation assumptions were satisfied for the constructs, although they were small

Class discussion What does it all mean??

Implications of overall variances

Implications of mediation and moderation

Implications of gender differences