On Optimality of Bayesian Wavelet Estimators

Abstract.  We investigate the asymptotic optimality of several Bayesian wavelet estimators, namely, posterior mean, posterior median and Bayes Factor, where the prior imposed on wavelet coefficients is a mixture of a mass function at zero and a Gaussian density. We show that in terms of the mean squared error, for the properly chosen hyperparameters of the prior, all the three resulting Bayesian wavelet estimators achieve optimal minimax rates within any prescribed Besov space     for p  ≥ 2. For 1 ≤  p  < 2, the Bayes Factor is still optimal for (2 s +2)/(2 s +1) ≤  p  < 2 and always outperforms the posterior mean and the posterior median that can achieve only the best possible rates for linear estimators in this case.     

Tax differentiation,lobbying, and welfare

To what extent a taxing authority should be granted the power to impose different tax schedules to different groups of taxpayers? Although the policy maker aims at maximizing social welfare, her tax policy may be distorted by the lobbying activity of taxpayers. In this political environment we characterize the conditions under which social welfare can be increased by restricting the set of tax instruments available to the policy maker; i.e., the scope of tax differentiation. We show that full differentiation is more costly, in terms of welfare distortions, when the lobbies are asymmetric in size, while minimal differentiation is more costly when the tax bases are asymmetric across different groups.     

Strategies for Europe proposals for science and technology policies industrial innovation in Europe

Europe's performance with respect to industrial innovation is compared to those of USA and Japan. The reasons for Europe's relatively poor performance are examined and related to institutional, cultural and social factors. An appropriate strategy for innovation in European industry is then defined.     

Predictive information and distance between past and future of a time series

A characterization for the nullity of the cosine angle between two subspaces of a Hilbert space is established. Given a time series x, we use this characterization in order to investigate the relationship between the notions of predictor space and distance between the information contained in the past and in the future of x. In particular, we prove that the predictor space of x coincides with the zero vector space {0} if and only if this distance achieves its maximum value.     

The Management of Redundancies in Europe: The Case of Italy

The paper presents the findings of comparative and interdisciplinary legal and economic study on managing labour redundancies in seven EU member countries. It is structured for comparability between the systems examined. The introductory section contains an account of the evolution of the Italian labour market, with special reference to redundancy trends, of the features of the programmes for managing redundancies, of the roles of firms and the ‘external environment’ in handling workforce adjustments. The second section presents a map of policies that work to prevent labour redundancies (preventive measures) such as flexibility, training etc. Next, the instruments for handling temporary labour redundancies (retentive measures) are examined (e.g. short-time working, temporary layoffs etc.). The following section is devoted to instruments and programmes involved in the management of permanent labour redundancies (expulsive measures), e.g. collective dismissals, severance pay etc. The final section provides an overall assessment of the Italian system for managing labour redundancies, and briefly discusses the national debate on the prospects for reform, in light of the principles and policies of convergence set forth by the European Union.     

Innovation through tradition in the Italian coffee industry: an analysis of customers’ perceptions

The extant literature reveals how firms may innovate by exploiting past competencies and resources, hence proposing innovation through tradition as an emerging strategy to compete. Previous research largely demonstrates that the effectiveness of an innovation strategy is strictly dependent on the capability of firms to communicate the right message to their customers. Therefore, leveraging products’ attributes becomes fundamental to strategically position their commercial offerings in the minds of the target audience. Nevertheless, despite the well-known relevance of this issue, scant attention has been devoted to investigate the product attributes that consumer’s associate with innovation and with tradition when companies deploy strategies based on “innovation through tradition”. Accordingly, our study aims at covering this gap, by empirically analyzing the consumers’ perception of innovation and tradition in the Italian coffee industry through a positioning analysis. Our research allowed us to identify two sets of product attributes that consumers associate with innovation and tradition. The results show that in many cases the innovation-related and tradition-related attributes are strongly negatively correlated, but in some case the correlation is weak or close to zero. These attributes reveal that in some cases innovation and tradition can be combined in the perception of consumers, rather than representing opposite constructs. This result suggests that companies can effectively communicate the strategy of innovation through tradition to the consumers’ minds, but this must be done by choosing the right attributes.     

Wavelet kernel penalized estimation for non-equispaced design regression

The paper considers regression problems with univariate design points. The design points are irregular and no assumptions on their distribution are imposed. The regression function is retrieved by a wavelet based reproducing kernel Hilbert space (RKHS) technique with the penalty equal to the sum of blockwise RKHS norms. In order to simplify numerical optimization, the problem is replaced by an equivalent quadratic minimization problem with an additional penalty term. The computational algorithm is described in detail and is implemented with both the sets of simulated and real data. Comparison with existing methods showed that the technique suggested in the paper does not oversmooth the function and is superior in terms of the mean squared error. It is also demonstrated that under additional assumptions on design points the method achieves asymptotic optimality in a wide range of Besov spaces.     

Response: Avuncularity and Kin Selection in Homosexuals: A Problematic Test or a Problematic Hypothesis?

Here we respond to Vasey et al.'s critical comments regarding our article, “Societal norms rather than sexual orientation influence kin altruism and avuncularity in tribal Urak-Lawoi, Italian, and Spanish adult males” (Camperio Ciani, Battaglia, &; Liotta, 2015 Camperio Ciani, A., Battaglia, U., &; Liotta, M. (2015). Societal norms rather than sexual orientation influence kin altruism and avuncularity in tribal Urak-Lawoi, Italian, and Spanish adult males. Journal of Sex Research. Advance online publication. doi:10.1080/00224499.2014.993748[Taylor &; Francis Online] , [Google Scholar], JSR doi:10.1080/00224499.2014.993748). The first regards the selection of the Urak-Lawoi population of Ko Lipeh, which is considered too modern and touristic to be adequate to test the kin selection and avuncular hypothesis for homosexuality. We provide historical evidence of the contrary, and show that the population at the inception of our 10 years research was indeed primitive and tribal, and probands actually grew and lived in such a society. Only a few years after the 2004 tsunami, the island was developed and invaded by mass tourism. The second comment regarded the statistical analysis and interpretation of data. We show that we consistently and conservatively considered the effects of all confounding variables, both with comparative tests, and by a series of multivariate regression analyses. This was the orthodox procedure approved by all other reviewers. In conclusion, even addressing these comments, we maintain that the kin selection and avuncularity hypothesis for homosexuality is not supported by empirical data even in this primitive and tribal society.     

Additive model selection

We study sparse high dimensional additive model fitting via penalization with sparsity-smoothness penalties. We review several existing algorithms that have been developed for this problem in the recent literature, highlighting the connections between them, and present some computationally efficient algorithms for fitting such models. Furthermore, using reasonable assumptions and exploiting recent results on group LASSO-like procedures, we take advantage of several oracle results which yield asymptotic optimality of estimators for high-dimensional but sparse additive models. Finally, variable selection procedures are compared with some high-dimensional testing procedures available in the literature for testing the presence of additive components.     

On large enterprises: new findings from a European comparison

The recent evolution of Italian capitalism shows the increasing relevance of large enterprises at three levels: the economic and institutional environment, the ownership structure, and the financing policy. A comparison of the financial structure of Italian large enterprises with those of other European countries (France, Germany, and Spain), using Bank for the Accounts of Companies Harmonised data, shows their financial fragility, where the prevalence of debt over equity justifies the still strong and close relationship between ownership control and management in their strategies and the prevalence of obsolete bank–firm relationships based on short-term external finance and multiple business lendings. These factors slow down firms’ expansion and consequently the need for companies to grow so as to face the new global market. Finance is confirmed as a determinant of growth both in size and in organisation. We conclude that a pivotal role for the growth of Italian firms lies in a “revised” relationship between size, governance, and the firms’ financial structure.