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Discriminant analysis of interval data: an assessment of parametric and distance-based approaches

Publication . Silva, A. Pedro Duarte; Brito, Paula

Building on probabilistic models for interval-valued variables, parametric classification rules, based on Normal or Skew-Normal distributions, are derived for interval data. The performance of such rules is then compared with distancebased methods previously investigated. The results show that Gaussian parametric approaches outperform Skew-Normal parametric and distance-based ones in most conditions analyzed. In particular, with heterocedastic data a quadratic Gaussian rule always performs best. Moreover, restricted cases of the variance-covariance matrix lead to parsimonious rules which for small training samples in heterocedastic problems can outperform unrestricted quadratic rules, even in some cases where the model assumed by these rules is not true. These restrictions take into account the particular nature of interval data, where observations are defined by both MidPoints and Ranges, which may or may not be correlated. Under homocedastic conditions linear Gaussian rules are often the best rules, but distance-based methods may perform better in very specific conditions.

2015Journal article

Restricted access

Sovereign CDS contagion in the European Union: a multivariate GARCH-in-variables analysis of volatility spill-overs

Publication . Oliveira, Maria Alberta; Santos, Carlos

GARCH-with-variables model is used to assess volatility contagion in the Eurozone Debt Crisis. Credit Default Swaps on sovereign debt with 3 years maturity are used as a reference financial instrument, covering the sample period from 2008-2013. Daily data on Credit Default Swaps is used. We conclude that there is strong statistical evidence of volatility contagion in CDS spreads from the Eurozone periphery to its core. However, the direction of contagion is contingent on the periphery and core countries being assessed. As such, German 3 year CDS on sovereign debt mean equation is to vulnerable to Portuguese and to Greek CDS volatility, whilst German sovereign CDS volatility is vulnerable to greek one day lagged sovereign volatility. Differently, France’s sovereign debt Credit Default Swaps are only exposed to Spanish and Italian sovereign CDS in the mean equation. Exposure to greek lagged one day volatility exists as well.

2014Conference object

Open access