We introduce peer effects in the costs of human capital acquisition into a model of statistical discrimination in labour markets. This creates a link between the level of segregation in social networks and racial disparities in job assignment and wages. We show that this relationship is characterized by discontinuities: there is a threshold level of segregation below which negative stereotypes become unsustainable, and steady-state skill levels can change dramatically. This change can work in either direction: skill levels may either rise or fall in both groups. Which of these outcomes arises depends on the population share of the disadvantaged group and on the distribution of the costs of human capital investments. We also examine the effects of affirmative action policies in the presence of peer effects and provide conditions under which such policies eliminate negative stereotypes.

Under the Agreement on Trade-Related Intellectual Property Rights, the World Trade Organization members are required to enforce product patents for pharmaceuticals. In this paper we empirically investigate the welfare effects of this requirement on developing countries using data for the fluoroquinolones subsegment of the systemic anti-bacterials segment of the Indian pharmaceuticals market. Our results suggest that concerns about the potential adverse welfare effects of TRIPS may have some basis. We estimate that the withdrawal of all domestic products in this subsegment is associated with substantial welfare losses to the Indian economy, even in the presence of price regulation. The overwhelming portion of this welfare loss derives from the loss of consumer welfare.

THE PROTECTION OF POOR HOUSEHOLDS in high-risk agrarian economies from shocks to their incomes has often been seen as a compelling motive for various forms of policy intervention including transfers of cash or food, credit subsidies, and public employment schemes (for a survey see Lipton and Ravallion (1995)). The desirability of such safety net policies clearly depends on how well pre-existing risk-sharing arrangements work. While it is commonly thought that, without effective policy intervention, rural households are vulnerable to village-wide shocks such as adverse prices or poor rains, it is less clear to what extent risk-sharing institutions within the village mitigate the effects of idiosyncratic income risk stemming, for instance, from ill-health or localized crop damage.2 Several recent papers have used household-level data to implement tests of risk-sharing that might inform such concerns.3 These tests are based on the proposition that with perfect risk-sharing, consumption at the household level should be insured against idiosyncratic risks and thus depend solely on the realization of the aggregate risk (Wilson (1968); Diamond (1967)). Townsend (1994) tests this implication of perfect intra-village risk-sharing using longitudinal household data on consumptions and incomes for three villages in India. He reports that the full-insurance hypothesis provides a surprisingly good benchmark in that household consumptions co-move and do not appear to be much influenced by contemporaneous own income. Our aim here is to examine the robustness of this potentially important finding. We have two main concerns. The first is that the specification Townsend adopts potentially biases his test towards the null hypothesis of full insurance because it yields inconsistent estimates of the key test parameter under a plausible alternative. We therefore estimate a different specification that generates consistent estimates under both the null and the alternative. Our second concern is that a particular form of measurement error in the consumption data Townsend uses may have further biased his results toward the null hypothesis of full-insurance. To address this concern, we use an instrumental variables procedure when we implement the test of consumption insurance with Townsend's consumption data. We also re-estimate the test equations with a measure of consumption derived from the same underlying primary data by an alternate method. Finally, Townsend reports 1Discussions with Robert Townsend stimulated our interest in this investigation. The staff of the

The welfare effects of trade shocks turn on the nature and magnitude of the costs workers face in moving between sectors. Using an Euler-type equilibrium condition derived from a rational expectations model of dynamic labor adjustment, we estimate the mean and variance of workers' switching costs from the US CPS. We estimate high values of both parameters, implying slow adjustment of the economy and sharp movements in wages in response to trade shocks. However, import-competing workers can still benefit from tariff removal; liberalization lowers their wages in the short and long run but raises their option value. (JEL E24, F13, F16)