ObjectivesThe Capabilities, Opportunities, Motivations, Behaviour (COM-B) model is
being used extensively to inform intervention design, but there is no standard measure
with which to test the predictive validity of COM or to assess the impact of interventions
on COM. We describe the development, reliability, validity, and acceptability of a
generic 6-item self-evaluation COM questionnaire.Design and methodsThe questionnaire
was formulated by behaviour change experts. Acceptability was tested in two independent
samples of health care professionals (N = 13 and N = 85, respectively) and a sample
of people with low socio-economic status (N = 214). Acceptability (missing data analyses
and user feedback), reliability (test-retest reliability and Bland-Altman plots) and
validity (floor and ceiling effects, Pearson's correlation coefficient [r], exploratory
factor analysis [EFA], and confirmatory factor analysis [CFA] were tested using a
national survey of 1,387 health care professionals.ResultsThe questionnaire demonstrated
acceptability (missing data for individual items: 5.9-7.7% at baseline and 18.1-32.5%
at follow-up), reliability (ICCs .554-.833), and validity (floor effects 0.6-5.5%
and ceiling effects 4.1-22.9%; pairwise correlations rs significantly <1.0). The regression
models accounted for between 21 and 47% of the variance in behaviour. CFA (three-factor
model) demonstrated a good model fit, (chi(2)[6] = 7.34, p = .29, RMSEA = .02, CFI
= .99, TLI = .99, BIC = 13,510.420, AIC = 13,428.067).ConclusionsThe novel six-item
questionnaire shows evidence of acceptability, validity, and reliability for self-evaluating
capabilities, opportunities, and motivations. Future research should aim to use this
tool in different populations to obtain further support for its reliability and validity.Statement
of contributionWhat is already known on the subject?The Capability, Opportunity, Motivation
(COM), Behaviour (-B) model is being used extensively to inform intervention design.The
lack of an accepted universal measure hinders progress in behaviour change.What does
this study add?There is evidence of acceptability, validity, and reliability for self-evaluating
COM.Our measure may be sufficiently generic for any behaviour or population, although
this requires further testing.
