Spanning tests in return and stochastic discount factor mean–variance frontiers: A unifying approach

We propose new spanning tests that assess if the initial and additional assets share the economically meaningful cost and mean representing portfolios. We prove their asymptotic equivalence to existing tests under local alternatives. We also show that unlike two-step or iterated procedures, single-step methods such as continuously updated GMM yield numerically identical overidentifying restrictions test, so there is arguably a single spanning test. To prove these results, we extend optimal GMM inference to deal with singularities in the long run second moment matrix of the influence functions. Finally, we test for spanning using size and book-to-market sorted US stock portfolios.     

Valuation of VIX derivatives

We conduct an extensive empirical analysis of VIX derivative valuation models before, during, and after the 2008–2009 financial crisis. Since the restrictive mean-reversion and heteroskedasticity features of existing models yield large distortions during the crisis, we propose generalisations with a time-varying central tendency, jumps, and stochastic volatility, analyse their pricing performance, and implications for term structures of VIX futures and volatility “skews.” We find that a process for the log of the observed VIX combining central tendency and stochastic volatility reliably prices VIX derivatives. We also uncover a significant risk premium that shifts the long-run volatility level.     

Indirect estimation of large conditionally heteroskedastic factor models,with an application to the Dow 30 stocks

We derive indirect estimators of conditionally heteroskedastic factor models in which the volatilities of common and idiosyncratic factors depend on their past unobserved values by calibrating the score of a Kalman-filter approximation with inequality constraints on the auxiliary model parameters. We also propose alternative indirect estimators for large-scale models, and explain how to apply our procedures to many other dynamic latent variable models. We analyse the small sample behaviour of our indirect estimators and several likelihood-based procedures through an extensive Monte Carlo experiment with empirically realistic designs. Finally, we apply our procedures to weekly returns on the Dow 30 stocks.     

Constrained Indirect Estimation

We develop generalized indirect estimation procedures that handle equality and inequality constraints on the auxiliary model parameters by extracting information from the relevant multipliers, and compare their asymptotic efficiency to maximum likelihood. We also show that, regardless of the validity of the restrictions, the asymptotic efficiency of such estimators can never decrease by explicitly considering the multipliers associated with additional equality constraints. Furthermore, we discuss the variety of effects on efficiency that can result from imposing constraints on a previously unrestricted model. As an example, we consider a stochastic volatility process estimated through a garch model with Gaussian or  t  distributed errors.     

TESTING UNCOVERED INTEREST PARITY: A CONTINUOUS‐TIME APPROACH*

Nowadays researchers can choose the sampling frequency of exchange rates and interest rates. If the degree of overlap is large relative to the sample size, standard GMM asymptotic theory provides unreliable inferences in uncovered interest parity (UIP) regression tests. We specify a continuous‐time model for exchange rates and forward premia robust to temporal aggregation, unlike existing discrete‐time models. We test the UIP restrictions on the continuous‐time model parameters and propose a novel specification test that compares estimators at different frequencies. Our results based on correctly specified models provide little support for UIP at both short and long horizons.     

Dynamic specification tests for dynamic factor models

We derive computationally simple expressions for score tests of misspecification in parametric dynamic factor models using frequency domain techniques. We interpret those diagnostics as time domain moment tests which assess whether certain autocovariances of the smoothed latent variables match their theoretical values under the null of correct model specification. We also reinterpret reduced‐form residual tests as checking specific restrictions on structural parameters. Our Gaussian tests are robust to nonnormal, independent innovations. Monte Carlo exercises confirm the finite‐sample reliability and power of our proposals. Finally, we illustrate their empirical usefulness in an application that constructs a US coincident indicator.     

The social profitability of business incubators: a measurement proposal

Abstract

Public business incubators are services placed at the disposal of original, generally newly-created projects, to which physical accompaniment, supervision and location are offered at prices below market value. They have as their aim to help set in motion and consolidate these firms during the stages in which they are weaker. The ultimate goal consists in favouring the generation of innovative firms, inducers of high-quality jobs, which can diversify the local business fabric, thus becoming a key tool in local development. The present paper provides a methodology to study the economic – but above all social – impact of business incubators, based on the examination of 40 from the 42 incubators existing in the Valencian Community (a Spanish autonomous region with five million inhabitants). Data analysis allows us to state that, although business incubators are not economically profitable since they need financial aids and public investment to start operating, they do have social profitability, insofar as the activity developed by entrepreneurs permits to provide public administrations – via taxes – with returns exceeding what was invested in these incubators. It has been determined that 2.8 euros (which can be applied to a variety of social areas) are collected via taxes for each euro spent to start them up.     

Econometric applications of positive rank-one modifications of the symmetric factorization of a positive semi-definite matrix

We present an algorithm for updating the symmetric factorization of a positive semi-definite matrix after a positive rank-one modification, which works even if the matrices involved do not have full rank. Recursive least squares and factor analysis provide two important econometric applications. An illustrative simulation shows that it can be potentially very useful in recursive situations.     

Underidentification?

We develop methods for testing that an econometric model is underidentified and for estimating the nature of the failed identification. We adopt a generalized-method-of moments perspective in a possibly non-linear econometric specification. If, after attempting to replicate the structural relation, we find substantial evidence against the overidentifying restrictions of an augmented model, this is evidence against underidentification of the original model. To diagnose how identification might fail, we study the estimation of a one-dimensional curve that gives the parameter configurations that provide the greatest challenge to identification, and we illustrate this calculation in an empirical example.     

Sequential estimation of shape parameters in multivariate dynamic models

Sequential maximum likelihood and GMM estimators of distributional parameters obtained from the standardised innovations of multivariate conditionally heteroskedastic dynamic regression models evaluated at Gaussian PML estimators preserve the consistency of mean and variance parameters while allowing for realistic distributions. We assess their efficiency, and obtain moment conditions leading to sequential estimators as efficient as their joint ML counterparts. We also obtain standard errors for VaR and CoVaR, and analyse the effects on these measures of distributional misspecification. Finally, we illustrate the small sample performance of these procedures through simulations and apply them to analyse the risk of large eurozone banks.