The arrival of the new

In this work we present a number of urn models in which, contrary to standard Pólya urns, the number of competing alternatives is not given from the outset but may increase with the arrival of innovations. We begin by describing a variant of Pólya urns, first introduced by Fred Hoppe, in which balls of previously non-existing colors are added with some (declining) probability. We then propose new variants in which the probability of the arrival of new colors is itself subject to adaptive change depending on the success of past innovations and discuss applications to evolutionary models of technologies and industries. We numerically simulate different specifications of these urns with adaptively changing mutation rate and show that they can account for complex patterns of evolution in which periods of exploration and innovation are followed by periods in which the dynamics of the system is driven by selection among a stable set of alternatives.     

A note on the symmetry of all Nash equilibria in games with increasing best replies

It is well known that a symmetric game has only symmetric (pure strategy) Nash equilibria if its best-reply correspondences admit only increasing selections and its strategy sets are totally ordered. Several nonexamples of the literature show that this result is generally false when the totality condition of the relation that orders the strategy sets is simply dropped. Making use of the structure of interaction functions, this note provides sufficient conditions for the symmetry of all (pure strategy) Nash equilibria in symmetric games where best-reply correspondences admit only increasing selections, but strategy sets are not necessarily totally ordered.     

Paulson's gift

We calculate the costs and benefits of the largest ever US government intervention in the financial sector announced during the 2008 Columbus-day weekend. We estimate that this intervention increased the value of banks’ financial claims by $130 billion (bn) at a taxpayers’ cost of $21–$44 billion with a net benefit between $86 and $109 bn. By looking at the limited cross section, we infer that this net benefit arises from a reduction in the probability of bankruptcy, which we estimate would destroy 22% of the enterprise value. The big winners of the plan were the bondholders of the three former investment banks and Citigroup, while the losers were JP Morgan shareholders and the US taxpayers.     

Great depression no. 2: finance and the real world

The current crisis is triggering off a number of overdue reflections and interventions. The need for closer regulation of the financial system is widely perceived to be necessary. That is no doubt necessary, but probably insufficient. A careful overhaul of the functions of the banking and financial system is also needed. Our forefathers, at the time of the Great Depression, were perhaps less demurring to trim a bloated financial system.

Some regulatory lessons to be drawn from the financial crisis

The article briefly outlines how the two major structural causes of the financial crisis have been a massive underestimation of the negative externalities potentially arising from malfunctioning of financial markets, and the policy decision to assign the production of an eminently public good, financial stability, to private parties. Both ideas have been a tenet of the so-called Greenspan doctrine. The crisis also shows that all regulators tend to be captured in the end, and thus any new legislation should contain bright-line rules, that might look inefficient when assessed with reference to the market they regulate, but are socially efficient, because it would be politically costly to alter them. Criminal sanctions, which after all are a social form of regulation, should also be strengthened.

Wage Differences By Gender: Evidence From Recently Graduated MBAS

In this paper we use data from the London Business School of measuredifferences in outgoing salaries of male and female graduates with a Master's in Business Administration degree. This is a relatively homogeneous population of individuals with very similar educational backgrounds, limited work histories, and who enter very similar jobs upon completion oftheir degree. Controlling for differences in individual characteristics as reported on application forms, we (r)nd that the starting salaries of women are approximately 8.6 percent less than men in identical occupations.     

Demand for environmentally friendly vehicles: A review and new evidence

Although the need for more environmentally friendly vehicles was recognized some decades ago, this new market has not yet established itself. Consumer behavior needs to be studied to ascertain when people will decide to purchase hybrid or electric vehicles rather than conventional ones. An in-depth review of the state-of-the-art has identified existing deficiencies and these are addressed in this paper, proposing a new approach that is applied to the case of Santander in Spain. Emphasis is placed on the role of citizens in researching the local market and their requirements with respect to such vehicles; our model assumes variability in user preferences, an utmost requirement as concluded from the literature review. Results suggest that the highest demand for cleaner vehicles would be achieved in two ways: firstly, by penalizing conventional vehicles in terms of costs/km; secondly, by providing incentives directed at lowering the purchasing price of hybrid and electric vehicles. Finally, as demand becomes more elastic, the preferred strategy should initially focus on hybrid vehicles.     

Comparison of four common data collection techniques to elicit preferences

We compare four common data collection techniques to elicit preferences: the rating of items, the ranking of items, the partitioning of a given amount of points among items, and a reduced form of the technique for comparing items in pairs. University students were randomly assigned a questionnaire employing one of the four techniques. All questionnaires incorporated the same collection of items. The data collected with the four techniques were converted into analogous preference matrices, and analyzed with the Bradley–Terry model. The techniques were evaluated with respect to the fit to the model, the precision and reliability of the item estimates, and the consistency among the produced item sequences. The rating, ranking and budget partitioning techniques performed similarly, whereas the reduced pair comparisons technique performed a little worse. The item sequence produced by the rating technique was very close to the sequence obtained averaging over the three other techniques.