Investigating theoretical explanations for behaviour change: The case study of ProActive The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials
Developing more effective behavioural interventions requires an underst and ing of the mechanisms of behaviour change , and methods to rigorously test their theoretical basis . The delivery and theoretical basis of an intervention protocol were assessed in ProActive , a UK trial of an intervention to increase the physical activity of those at risk of Type 2 diabetes ( N = 365 ) . In 108 intervention sessions , behaviours of facilitators were mapped to four theories that informed intervention development and behaviours of participants were mapped to 17 theoretical components of these four theories . The theory base of the intervention specified by the protocol was different than that delivered by facilitators , and that received by participants . Of the intervention techniques delivered , 25 % were associated with  theory of planned behaviour ( TPB )  , 42 % with  self-regulation theory ( SRT )  , 24 % with  operant learning theory ( OLT )  and 9 % with  relapse prevention theory ( RPT ) .  The theoretical classification of participant talk showed a different pattern , with twice the proportion associated with OLT ( 48 % ) , 21 % associated with TPB , 31 % with SRT and no talk associated with RPT . This study demonstrates one approach to assessing the extent to which the theories used to guide intervention development account for any changes observed Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more
OBJECTIVE To systematic ally investigate the extent and type of theory use in  physical activity and dietary interventions  , as well as associations between extent and type of theory use with intervention effectiveness .