Annex B: Classification of intervention effectiveness
Drawing on definitions and terminologies used by NICE and DFiD, a comprehensive classification system has been developed to categorise the effectiveness of interventions based on available evidence. The decision making tool below has been used to determine effectiveness ratings throughout this report on what works to promote health and wellbeing among prison populations. It has been used alongside a purposively designed decision tree presented in Annex C.
Evidence that the intervention is associated with a positive impact on health and wellbeing, based on a moderate or strong evidence base. Due to the complexity of causality, an 'effective' intervention should be considered one that contributed towards improved health or wellbeing rather than one that single-handedly accounts for an increase in health or wellbeing.
Findings were positive but not to the extent that they constituted evidence that an intervention was 'effective', this could be:
(i) in cases where an intervention has a positive impact on an intermediate outcome, rather than in improving health and wellbeing itself
(ii) where authors noted a positive change, but expressed doubts as to whether the intervention could confidently be said to have contributed to this (e.g. due to evidence being rated as "weak" or the other factors potentially having an impact).
Findings of individual article -
(i) An individual article that finds varied impact of a single intervention across research sites, or populations.
(ii) An article examining multiple strands of an interventions that finds some were effective/promising and others not.
Findings from a number of studies-
(i) Where there have been a number of studies and the results contrast – e.g. some found positive effects and some did not.
(ii) Similarly, a body of evidence that is mostly comprised of individual articles finding a 'mixed' impact of interventions would be considered 'mixed' overall.
No evidence of effect (positive or negative) of the intervention on improving health or wellbeing or includes moderate or strong evidence found the intervention had no effect on improving health or wellbeing.
Negative effect/ Potentially harmful
Evidence that the intervention is associated with worse health and wellbeing outcomes (e.g. worse than at the start of the intervention, or worse than for a control group).
Insufficient evidence to make a judgement on impact.
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