Intervention studies


Randomised controlled trial


·       Considered the gold standard design to evaluate an intervention

·       Controlled (must be a relevant control condition for comparison)

Randomised (participants must be randomly assigned to treatment/control conditions)

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Cross-over study

          Participants complete both conditions one after the other

·       Can compare treatment to well-matched control (within-subjects)

Can be combined with RCT

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Quasi-experimental study

·       When RCTs aren’t possible

·       Still comparing treatment and control but not randomly allocated

·       Appropriate when there are practical or ethical barriers to random allocation

·       Sort of experimental

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Belief in an inactive treatment produces positive effects

Being studied can affect our behaviour, and believing we are receiving a treatment can affect outcomes

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·       Can it work?

       Assessed in controlled lab/clinical setting

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·       does it work?

      Does it produce sustained benefits over time?

      Assessed in realistic setting

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if it does work, is it a cost-effective way to achieve those benefits?

Evaluate costs and benefits

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Feasibility study

Feasibility studies can be used before investing resources in full scale intervention studies, to assess whether the proposed intervention is feasible

Acceptability: how do the intended recipients of an intervention react to the proposed design and materials?

Practicality: can the proposed intervention be delivered within the time and resources available?

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whether participants followed the intervention as intended

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