JEL classification: C31 I11 Keywords:Demand for health services Matching estimator Moral hazard Portuguese health system a b s t r a c tWe estimate the impact of extra health insurance coverage beyond a National Health System on the demand for several health services. Traditionally, the literature has tried to deal with the endogeneity of the private (extra) insurance decision by finding instrumental variables. Since a priori instrumental variables are hard to find we take a different approach. We focus on the most common health insurance plan in Portugal, ADSE, which is given to all civil servants and their dependents. We argue that this insurance is exogenous, i.e., not correlated with the beneficiaries' health status. This identifying assumption allows us to estimate the impact of having ADSE coverage on the demand for three different health services using a matching estimator technique. The health services used are number of visits, number of blood and urine tests, and the probability of visiting a dentist. Results show large positive effects of ADSE coverage for number of visits and tests among the young (18-30 years old) but only the latter is statistically significantly different from zero. The effects represent 21.8% and 30% of the average number of visits and tests for the young. On the contrary, we find no evidence of moral hazard on the probability of visiting a dentist.

In this paper a consistent estimator for the Binomial distribution in the presence of incidental parameters, or ÿxed e ects, when the underlying probability is a logistic function is derived. The consistent estimator is obtained from the maximization of a conditional likelihood function in light of Andersen's work. Monte Carlo simulations show its superiority relative to the traditional maximum likelihood estimator with ÿxed e ects also in small samples, particularly when the number of observations in each cross-section, T , is small. Finally, this new estimator is applied to an original dataset that allows the estimation of the probability of obtaining a patent.

Bilateral Market Power and Vertical Integration in the Spanish Electricity Spot Market*The Spanish electricity spot market is highly concentrated both on the seller and the buyer side. Furthermore, unlike electricity spot markets in other deregulated electricity systems, large buyers and sellers are typically vertically integrated. This allows both large net sellers and large net buyers to strategically influence the spot market price. We develop a supply function model of this market to analyse the impact of market power on prices and productive efficiency and use it empiricially to detect such bilateral market power. Our estimates suggest that market power has had little impact on spot market prices but that substantial productive inefficiencies may have arisen from the exercise of bilateral market power.JEL Classification: L13, L41 and L94

Policy interventions that increase insurance coverage for infertility treatments may affect fertility trends, and ultimately, population age structures. However, such policies have ignored the overall impact of coverage on fertility. We examine short-term and long-term effects of increased insurance coverage for infertility on the timing of first births and on women's total fertility rates. Our main contribution is to show that infertility mandates enacted in the United States during the 80s and 90s did not increase the total fertility rates of women by the end of their reproductive lives. We also show evidence that these mandates induced women to put off motherhood.

If public funds are aHocated efficiently, then an increase in funding should improve the performance of substance abuse treatment programs. In the data used in this paper, performance (measured as abstinence rates) and expenditures per patient are not positively correlated. One explanation is that funding is endogeneous, i.e. programs treating more difficult patients receive more funding. The data comes from aH Maine's outpatient drug-free prograrns that received public funding between 1991 and 1994. After controlling for endogeneity, this paper concludes that the marginal impact of expenditures per patient on abstinence rates is small and statistically insignificantly different from zero.