Here is an article looking at the coverage of two different sales-based approaches to distributing a complementary feeding supplement to infants and young children in Ghana. The assessment / evaluation approach is interesting in that it uses indicators or raw coverage, met need (i.e. coverage in risk groups), and "coverage ratio" wich assesses how goo the program is at targeting at-risk populations. It also uses the S3M (simple spatial sampling) framework.

I hope this is useful.