Monitoring & Evaluation is that part of the commissioning process which ensures that the investment of resources has delivered the desired service outcomes.
When dealing with small or hard to reach populations qualitative methods including focus groups and depth interviews can be useful. Community organisations can be useful partners in consultation or may provide input directly.
For services which are used more widely larger scale qualitative methods may be appropriate as qualitative methods may appear ‘rigged’. Surveying population samples through telephone interviews or as part of a wider services survey can be cost effective and result in a higher response rate. Surveys of users are useful but intrinsically self selecting. After all they tell you nothing about the perceptions of those who are excluded from services.
The Monitoring and Evaluation page of this site deals extensively with what to measure, how to measure, how much to measure and when to measure.