page 5 where A(2 ) is a linear homogeneous increasing function of input prices, the parameters ui and s are strictly positive and B3 is greater than or equal to one. The parameters 1i and s determine respectively the intercept of the isocast curve on the e axis and the degree of returns to scale of the production technology. The parameter a measures the degree of complementarity in the production of the two outputs of an integrated rural primary health care program. It us related to 6, the elasticity of product transformation, by _6 -_ 1/(B1 Figure 1 depicts the shape o , :e isocost or production possibility frontier associated with equation (2) for foar different values of B. W`ien B equals one, there is no complementarity between e and v and the isocost curve is linear as in Figure la. For larger values of B t&,e isocost curve bows outward, demonstrating increasing complementarity in the production of encounters and vaccinations. As a approaches infinity, the two ouCptUL. become joint products which should be produced in fixed proportions if both im prove health status.[81 The next paragraphs bring to bear a few "stylized facts" in order to specify the relative magnitudes of the parameters of equation (2) for each of the two competing strategies.

Evidence from tie Ivory Coast supports the observation that vertically organized mobile vaccination teams can be as much as twice as cost-effective as fixed centers at the delivery of vaccination services alone (Shepard, Sanoh and Coffi, 1982b). The observed difference in cost-effectiveness is probably due to the greater accountability and compliance that are properties of vertically organized management structures, the tight task definitions of the vaccination teams, their mobility and flexibility which allow them to go where the people are on a given day, the speed of their itinerary and the physical limit on the number of employees per vehicle which acts as an effective check on the political pressure to increase employment on the teams.

To capture this stylized fact, set e equal to zero in equation (2) and solve for v: The assumption that Strategy M is twice as cost-effective as Strategy F at the production of vaccinations alone can then be represented by supposing that, for the same recurrent budget C*, the actainable value of v from equation (3) is twice as large for Strategy M values of A(2) and s as it is for Strategy *F values.d9l Call * the number of vaccinations produceable from budget C by Strategy F, V . Then the nu%ber of vaccinations produceable from the same budget by Strategy M will be 2V . Advocates of fixed centers argue that once such a center is operating at a given annual recurrent budget and one of its staff is making periodic vaccination visits to the surrounding villages, the number of vaccinations that would have to be foregone for the traveling staff member to also supervise and support a VHW in each village would be quite small. In other words, the fixed center could add VH W supervision to its tasks at little "opportunity cost" in terms of .oregone vaccinations. The technology of producing both VH W services and vaccinacions from a fixed center can thus be characterized by substantial complementarity.