The finite-sample size of the BDS test for GARCH standardized residuals

This paper uses a multivariate response surface methodology to analyze the size distortion of the BDS test when applied to standardized residuals of rst-order GARCH processes. The results show that the asymptotic standard normal distribution is an unreliable approximation, even in large samples. On the other hand, a simple log-transformation of the squared standardized residuals seems to correct most of the size problems. Nonethe-less, the estimated response surfaces can provide not only a measure of the size distortion, but also more adequate critical values for the BDS test in small samples.

Growth process in business and social entrepreneurship: the case of Brazil

The purpose of the dissertation is to investigate in depth the difference between the challenges social and business entrepreneurs face in the growth phase of their business in the particular environment of Brazil. This objective has been achieved through a two-steps methodology. The first step is a set of in-depth interviews carried out with industry experts such as professors, venture capitalists, consultants, fund managers or people involved in the support of growing startups (i.e. accelerators). These interviews allowed, first, to build a general perspective on the environment entrepreneurs operate into and to identify a list of challenges entrepreneurs face in the growth process of their business. This list was completed with the additional challenges identified in the previous literature. The second step of the methodology was to test the relevance of these challenges in the mind and experience of social and traditional entrepreneurs. A questionnaire was then submitted to 145 social and 286 traditional entrepreneurs. The results were statistically analyzed to test the relative relevance of these challenges for one group of entrepreneurs with respect to the other. The outcome of the analysis was significant. The most relevant challenges identified were, for both groups, taxation, bureaucracy, finding the right employees, creating effective teams, measuring firm performance and social value creation and obtaining funds. On the other side motivation, innovation, competition and lack of market space for growth represented the least relevant issues in the minds of entrepreneurs. This rank however did not differ significantly from social to traditional entrepreneurs. This testifies that in Brazil social and traditional entrepreneurs face the same set of challenges despite the widespread belief of the opposite.

Invariant tests in an instrumental variables model with unknown data generating process

In this work we focus on tests for the parameter of an endogenous variable in a weakly identi ed instrumental variable regressionmodel. We propose a new unbiasedness restriction for weighted average power (WAP) tests introduced by Moreira and Moreira (2013). This new boundary condition is motivated by the score e ciency under strong identi cation. It allows reducing computational costs of WAP tests by replacing the strongly unbiased condition. This latter restriction imposes, under the null hypothesis, the test to be uncorrelated to a given statistic with dimension given by the number of instruments. The new proposed boundary condition only imposes the test to be uncorrelated to a linear combination of the statistic. WAP tests under both restrictions to perform similarly numerically. We apply the di erent tests discussed to an empirical example. Using data from Yogo (2004), we assess the e ect of weak instruments on the estimation of the elasticity of inter-temporal substitution of a CCAPM model.