For evaluations a combination of qualitative and quantitative (participatory) analysis methods are used.
The quantitative part produces easy to interpret (for donors, management and field staff, beneficiaries and other actors) information on output and efficient use of resources. It deals with the (often) available information. The qualitative analysis complements the evaluation and gives the complete picture. It detects interesting or worrying trends and gives to what extend the intervention contributed to the outcomes and impact.
By using participatory methods the evaluation becomes part of organisational learning.