The substitution of health workers (e.g. high-level
cadres substituted by mid-level cadres) has been sug-
gested in the literature as one of the alternatives to
deal with the shortage of health professionals in poor
countries at a lower cost [10-12]. However, the evi-
dence regarding skill mix in the health care work-
force, and in particular the degree of substitutability
between different cadres, is still limited and mostly
descriptive [13].