6. Acknowledgement

The authors thank an anonymous referee for very useful comments on a previous draft. This research was supported in part by NIH RO1 HD37276-01 and by TransCoop Program of the German-American Academic Council. The data used in this paper were collected with funding from USAID's Evaluation Project (Watkins and Naomi Rutenberg Co-PI's) and The Rockefeller Foundation (for a larger project including Malawi with Watkins and Eliya Zulu Co-PI's).