page 22 Suppose aul, implying constant returns to scale in trarsport. Then the asaumptions of Table 6 yield an estimate of Uf %qual to 10.6. If -!n the other hand the mobile team achieves substantial economies of scale in transport that would not be available for smaller amounts of travel by a VH W supervisor attached to a fLxed center, then the value Of Po' is estimated to be **as** low as 3.1 when s - 0.7. At this value of s, total transport costs rise only seven percent for every tan percent increase in Q. If the commercial trucking industry in an LDC benefited from economies of scale as great as this, one would not expect to find any small independent truckers left in the country.

According to the decision rule, if b/a is greater than the ratio of Uf to a function of B (or of d), Strategy M is more cost-effective than Strategy F. However, the functicn of a vanes between one (when B approaches infirity) and two (when B approaches one). Thus if b/s is greater than Pf, or less than p /2 the value of B has no effect on the decision. In the former case, Strategy h lis more cost-effective and in the latter case Strategy F dominates. Only iE b/a is between these two bcunds is B important.

4. Applications of the Decision Rule. Table 7 presents four estimates of b/a across the top and four estimates of uf down the left side. The cells of the table are divided into three sections by aotted lines. Cels to the northwest, where b/a is less than P<sup>1</sup> f/<sup>2</sup> , are marked with an F to indicate that **these** parameter values lead to the choice of Strategy F regardless of **the** degree of complementarity of the f;xed center cost function. Cells to the southeast contain an M to indicate the reverse. Only in the cells between the two dotted lines does the strategy choice depend on the value of B. Instead of an F or an M, these cells contain the critical value of B (and in parentheses the critical value of 6) above which (below which) the decision rule would prescribe Strategy F.

For reasons explained above, column (2) for Java ard column (4) for Ghana seem more plausible than columns (1) and (3) respectively. Also constant or only mildly increasing .,eturns to scale, as represented by rows (A) and (B) seem more plausible than the more extreme economies of scale as represented by rows (C) and (D). Within these cells, Strategy F unequivocally dominates Strategy M in Java, regardless of the complementarity in the Javanese fixed centers.

NOTES TO TABLE 6 (continued):

- Item Fl: The average number of vaccinations per year performed by the two of the fourteen rural fixed health centers in Abengourou which perform such vaccinations as reported by Sanoh (1983, Table 6).

- Item F2: The average total cost for producing these vaccinations. (Sanoh, 1983, Table 3). Item F3: In West African VHW worker projects, 3 supervisions per year is a minimum recommendation. See for example Over (1980, 1982).

Item F4: Item F2/item F3.

- Item F5: The assumption used in Grosse et al (1979). At one VEW per 500 inhabitants, this figure implies 45 encounters per week. In a sample of nine Senegalese villages visited in the summer of 1979, Over (1980) found the average VUW was seeing 6.5 villagers a day, with a standard devaation of 3.9. This small sample thus supports the estimate from Grosse et aL