all providers with a sign advertising medical care within a 15-minute walking radius around the perimeter of the area of the household survey were noted. This formed a "census" recording the quali fi cations, age, gender and experience of providers in the universe.

From this set, a sample of 20-25 practitioners were drawn from among those who had been visited (with sampling weights proportional to the number of all visits by households) and 10 from the group that had not been visited by anyone in the household sample in each of the seven neighborhoods.<sup>7</sup> From this sample, 205 providers participated in the study after a 15 percent rate of non-compliance.<sup>8</sup> While most practitioners (163) were in clinics staffed by a single person, we also interviewed practitioners in hospitals (public and private) and public clinics with multiple providers. In these cases, we interviewed at least two providers in every facility; for hospitals, interviews were conducted in the out-patient department that serves walk-in patients.

For each of the 205 providers, we completed a two-stage inquiry. In the fi rst part we administered fi ve "vignettes" or hypothetical cases acted out by two interviewers (the provider was aware of the role playing) to every provider in the sample (Das and Hammer 2005). One of the interviewers acted as the "patient" while the other recorded questions the doctor asked and answered those that the patient would not know the answer to, such as the results of an examination or tests recommended. Diagnoses reached and the treatments prescribed were also noted. This large volume of information was summarized by use of item response theory (IRT) that gave each doctor a score derived as a weighted average of the relevant questions asked and treatments prescribed–the weights being determined via the statistical technique. We call this score the “competence” of the provider.<sup>9</sup> The main results of that study relevant for this paper were as follows.

- Private providers with MBBS degrees were most competent with average competence one standard deviation higher than their non-MBBS counterparts and a distribution of competence skewed to the left.

- Private practitioners without an MBBS degree were least competent on average but with a distribution skewed to the right (some were quite good).

- The distribution of competence in the public sector was dispersed and distinctly bimodal, a feature that came out clearly with the IRT scoring method. The two parts of the distribution corresponded quite closely to doctors who served in small clinics and dispensaries versus those in large, general hospitals (again, among the most prestigious in the country). This division will continue to be important here.

- Private MBBS doctors were slightly better, on average, than those in the public general hospitals. Private practitioners without an MBBS were somewhat worse, on average, than public MBBS doctors in small clinics, but not by much.

> 7 Some neighborhoods had fewer than 25 different providers which is the reason for the range.

> 8 Reasons for non-compliance were evenly divided between providers who had left the locality or could not be located (in some cases, a household may have visited the provider a single time and could not remember the address) and those who refused. It is hard to sign the direction of the bias–refusals could either re fl ect higher quality with a greater opportunity cost of time or lower quality if the provider was scared of personal repercussions from the survey.

> 9 IRT can be thought of as principal components or factor analysis properly treating the large number of dichotomous variables. The analogue of the fi rst principle component or factor is our measure of competence.

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