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Assessing the feasibility of conducting a randomised controlled trial or other outcome study of P-ASRO

Researchers: Jane Kerr
Published: January 2011


This study explored the feasibility of evaluating the success of P-ASRO by randomised control trial (RCT) or other outcome study.

What is P-ASRO?

P-ASRO (Prisoners – Addressing Substance Related Offending) is the name of a cognitive-behavioural intervention delivered to prisoners whose substance use means they are more likely to commit crime.


A RCT or other outcome evaluation of P-ASRO is feasible and staff and offenders were broadly in support of this. The ethical, clinical, legal and practical challenges cited throughout the literature and by staff and offenders can be managed to enable a RCT to take place. Stakeholders support the idea of an evaluation and recognise the need for high quality evidence that demonstrates whether P-ASRO is achieving its goals.

However there were concerns about:

  • the need to manage any negative effects of random allocation on offenders. Therefore it would be necessary for random allocation to be carried out by an external team and to have measures in place to manage any negative impacts on offenders.
  • the type of intervention provided for the control group and how this could affect an evaluation measuring the relative impact of P-ASRO.
  • whether the number of offenders currently taking part in P-ASRO would produce a sufficiently large sample size for useful results. This could be resolved by changing the way P-ASRO was delivered, or/and widening the eligibility criteria.

Those taking part in an interview/ group discussion felt that any study for evaluating P-ASRO should be underpinned by:

  • clearly defined outcome measures to demonstrate that this programme is ‘working’
  • a clear strategy for disseminating its findings
  • and support from across the prison estate, including the Ministry of Justice, operational staff and offenders


The research was primarily qualitative and comprised four distinct stages:

  • interviews with strategic stakeholders
  • case studies in prisons (interviews and group discussions with staff and offenders)
  • telephone interviews with Counselling, Assessment, Referrals, Advice and Throughcare (CARAT) service workers
  • a workshop with treatment managers. 

Read the report