This understanding of the comparator group will be gained early in the study through discussions with staff in each probation service. Primary and secondary outcome measures The primary selleck outcome of the study

is quality of life and well-being derived from the Clinical Outcome in Routine Evaluation–Outcome Measure (CORE-OM). CORE-OM has been validated among offender populations46 47 and can be used to derive QALYs.48 The 34 items cover four dimensions: subjective well-being; problems/symptoms; life functioning; and risk/harm.49 Secondary outcomes are: Individual level data on re-offending rates over a max 18-month period obtained from individual level data from the Police National Computer. Mental health derived from Warwick-Edinburgh Mental Well-being Scale (WEMWBS).45 Measures of smoking, alcohol, drug use, diet and physical activity adapted from General Lifestyle Survey50 and Health Survey of England.51 Measures of the relatedness to nature.52 53 Exploration of health utility as derived from CORE-OM.49 Based on CORE-OM, health states can be valued and quality adjusted life years (QALYs) derived permitting a cost-utility analysis.48 Exploration of the cost per re-offending event avoided due to attendance on a care farm. Sample and recruitment processes As a pilot study, a conventional sample size calculation is not appropriate as the study’s main aim is to assess feasibility, recruitment

and follow-up rates, clarify selection biases and effects of confounding. As there are no hard and fast rules for judging the sample size for a pilot study,

we judge an appropriate sample size to be 300 participants recruited across the three care farms and comparator sites. This will be sufficient to allow us to determine a sample size for a follow-on study that takes account of between-care farm effects and the possible effects of bias (ie, response rates and drop-out). With an expected loss to follow-up of 40%, this will allow a total of 180 participants (90 care farm attendees and 90 comparator location attendees) with both baseline and follow-up data. Using three sites will enable the assessment of variation between care farms and with comparator sites, in terms of: recruitment and follow-up rates, allocation decisions (ie, confounders), selection Entinostat biases and outcome measures. In order to meet this target of 300 participants, we plan to recruit 60 participants over a 1-year period from care farm 1 and 60 from comparator 1. Recruitment will start at a later date in the other two care farms and comparators. Forty-five participants will be recruited from care farm 2 and 45 from comparator 2. Similarly, 45 will be recruited from care farm 3 and comparator 3. These participants will be recruited over a 9-month period. In total therefore, 150 participants will be recruited from all three care farms and 150 from across the three comparator locations.