Randomisation and masking
self-harm
The completed baseline assessments were sent by the trained researchers to the Trial Manager who then contacted the off-site randomisation centre, where eligibility was re-checked, baseline measures recorded and participant trial numbers assigned. Treatment assignment was determined using block randomisation controlling for gender, age, and type of self-harm behaviour. For the block randomisation, study site, age group (> 30 or <  = 30), gender and type of self-harm were included as strata. However, self-harm was only included as any chemical (including bleach and pesticides) or other. A randomisation list was generated using online resource-sealed envelopes. The online resource was used with block sizes 2, 4, 6 and 8.The off-site statistician and research team carrying out follow-up assessments were blinded to treatment allocation. Trial participants and therapists were not blinded to treatment allocation as evidence suggests that blinding of participants and therapists may compromise the effects of the active ingredients of the psychological intervention. Effective delivery of a particular psychological intervention requires extensive training, which would be difficult to implement with the blinding intact [