Service evaluation is designed and conducted solely to define or judge current care and should answer the question: "What standard does this service achieve?"
It should measure current service without reference to a standard and involve an intervention in use only. (The choice of treatment is that of the clinician and patient according to guidance, professional standards and/or patient preference and this should happen before service evaluation). There should be no randomisation.
Service evaluation usually involves analysis of existing data but may include administration of interview or questionnaire.
Service development or improvement seeks to find out what improvement can be achieved within that service only.
It may involve a new intervention or service, or one that is new to that context, but there should be no randomisation and the choice of treatment, care or services is that of the care professional and patient/service user according to guidance, professional standards and/or patient/ service user preference.
Service evaluation / improvement / development work does not require NHS REC review.