Recent empirical studies in regional science and urban economics show that agglomeration economies may be one source of the uneven distribution of economic activities and economic growth across cities and regions. At the same time, the body of research into the importance of agglomeration...

Many statistical applications require an estimate of a covariance matrix and/or its inverse. When the matrix dimension is large compared to the sample size, which happens frequently, the sample covariance matrix is known to perform poorly and may suffer from ill-conditioning. There already...

Models for realized covariance matrices may suffer for the curse of dimensionality as more traditional multivariate volatility models(such as GARCH and stochastic volatility). Within the class of realized covariance models we focus on the Wishart specification introduced by Gourieroux et al....

Empirical studies document that equity portfolios constructed to have the lowest possible risk have surprisingly high average returns. We derive an analytic solution for the long-only minimum variance portfolio under the assumption of a single-factor covariance matrix. The equation for optimal...