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arXiv2010

Fundamental defect of the macroeconomic thinking as one of the main causes of the crisis endured

The main points of the first section of the article written by S.I. Chernyshov, A.V. Voronin and S.A. Razumovsky arXiv:1003.4382), which deals with the fundamental bases of the macroeconomic theory, have been analyzed. An incorrectness of the Harrod's model of the economical growth in its generally accepted interpretation was specifically considered. The inevitability of the economic crisis has been shown to follow directly from the premises of this model. At the same time there is an opportunity to realize the damping strategies.

q-fin.GN↗
arXiv2010

Fifteen years of econophysics: worries, hopes and prospects

This anniversary paper is an occasion to recall some of the events that shaped institutional econophysics. But in these thoughts about the evolution of econophysics in the last 15 years we also express some concerns. Our main worry concerns the relinquishment of the simplicity requirement. Ever since the groundbreaking experiments of Galileo some three centuries ago, the great successes of physicists were largely due to the fact that they were able to decompose complex phenomena into simpler ones. Remember that the first observation of the effects of an electrical current was made by Alessandro Volta (1745-1827) on the leg of a frog! Clearly, to make sense this observation had to be broken down into several separate effects. Nowadays, with computers being able to handle huge amounts of data and to simulate any stochastic process no matter how complicated, there is no longer any real need for such a search for simplicity. Why should one spend time and effort trying to break up complicated phenomena when it is possible to handle them globally? On this new road there are several stumbling blocks, however. Do such global mathematical descriptions lead to a real understanding? Do they produce building blocks which can be used elsewhere and thus make our knowledge and comprehension to grow in a cumulative way? Should econophysics also adopt the "globalized" perspective that has been endorsed, developed and spread by the numerous "Complexity Departments" which sprang up during the last decade?

physics.soc-ph↗
arXiv2010

Wealth distribution: To be or not to be a Gamma?

We review some aspects, especially those we can tackle analytically, of a minimal model of closed economy analogous to the kinetic theory model of ideal gases where the agents exchange wealth amongst themselves such that the total wealth is conserved, and each individual agent saves a fraction (0 < lambda < 1) of wealth before transaction. We are interested in the special case where the fraction lambda is constant for all the agents (global saving propensity) in the closed system. We show by moment calculations that the resulting wealth distribution cannot be the Gamma distribution that was conjectured in Phys. Rev. E 70, 016104 (2004). We also derive a form for the distribution at low wealth, which is a new result.

physics.soc-ph↗
arXiv2010

Crude oil and motor fuel: Fair price revisited

In April 2009, we introduced a model representing the evolution of motor fuel price (a subcategory of the consumer price index of transportation) relative to the overall CPI as a linear function of time. Under our framework, all price deviations from the linear trend are transient and the price must promptly return to the trend. Specifically, the model predicted that "the price for motor fuel in the US will also grow by 50% by the end of 2009. Oil price is expected to rise by ~50% as well, from its current value of ~$50 per barrel". The behavior of actual price has shown that this prediction is accurate in both amplitude and trajectory shape. Hence, one can conclude that the concept of price decomposition into a short-term (oscillating) and long-term (linear trend) components is valid. According to the model, the price of motor fuel and crude oil will be falling to the level of $30 per barrel during the next 5 to 8 years.

q-fin.GN↗
arXiv2010

A discussion of stock market speculation by Pierre-Joseph Proudhon

The object of this contribution is to present the ideas behind the thinking of the French economist Pierre-Joseph Proudhon (1809-1865) in relation to the causes and effects of Stock market speculation. It is based upon the works of this author but particularly on his "Manuel du spéculateur à la Bourse" (Stock Market Speculator Manual) edited in 1857 in Paris. Compared to the markets of today, however, the stock market described by Proudhon appears embryonic. Nevertheless it represents the location for transactions in financial assets, commodities, precious metals and even some transactions involving options. This contribution is organised in the following manner - the first section is devoted to the development of Proudhon's thought in relation to speculation. It is divided into two parts. The first part is dedicated to Pierre-Joseph Proudhon's definitions of stock market speculation or gambling with shares that for him served no purpose either from a human or economic perspective and was therefore condemnable and to be contrasted with entrepreneurial speculation that, even though it is a highly-risky activity, involves the spirit of enterprise and provides the lifeblood of economic growth. The second part allows us to present Pierre-Joseph Proudhon's propositions in relation to restricting the speculation that he considers obnoxious. The second section has two objectives: one part places in perspective the views of Proudhon and the characteristics of stock market activity under the Second Empire whilst the other part examines current-day aspects of the characteristics evoked by Proudhon. We are interested especially in the question of the regulation and that of the relevance today of certain accounting practices.

q-fin.GN↗
arXiv2014

Stable-1/2 Bridges and Insurance

We develop a class of non-life reserving models using a stable-1/2 random bridge to simulate the accumulation of paid claims, allowing for an essentially arbitrary choice of a priori distribution for the ultimate loss. Taking an information-based approach to the reserving problem, we derive the process of the conditional distribution of the ultimate loss. The "best-estimate ultimate loss process" is given by the conditional expectation of the ultimate loss. We derive explicit expressions for the best-estimate ultimate loss process, and for expected recoveries arising from aggregate excess-of-loss reinsurance treaties. Use of a deterministic time change allows for the matching of any initial (increasing) development pattern for the paid claims. We show that these methods are well-suited to the modelling of claims where there is a non-trivial probability of catastrophic loss. The generalized inverse-Gaussian (GIG) distribution is shown to be a natural choice for the a priori ultimate loss distribution. For particular GIG parameter choices, the best-estimate ultimate loss process can be written as a rational function of the paid-claims process. We extend the model to include a second paid-claims process, and allow the two processes to be dependent. The results obtained can be applied to the modelling of multiple lines of business or multiple origin years. The multi-dimensional model has the property that the dimensionality of calculations remains low, regardless of the number of paid-claims processes. An algorithm is provided for the simulation of the paid-claims processes.

q-fin.GN↗
arXiv2010

GDP Trend Deviations and the Yield Spread: the Case of Five E.U. Countries

Several studies have established the predictive power of the yield curve in terms of real economic activity. In this paper we use data for a variety of E.U. countries: both EMU (Germany, France, Italy) and non-EMU members (Sweden and the U.K.). The data used range from 1991:Q1 to 2009:Q1. For each country, we extract the long run trend and the cyclical component of real economic activity, while the corresponding interbank interest rates of long and short term maturities are used for the calculation of the country specific yield spreads. We also augment the models tested with non monetary policy variables: the countries' unemployment rates and stock indices. The methodology employed in the effort to forecast real output, is a probit model of the inverse cumulative distribution function of the standard distribution, using several formal forecasting and goodness of fit evaluation tests. The results show that the yield curve augmented with the non-monetary variables has significant forecasting power in terms of real economic activity but the results differ qualitatively between the individual economies examined raising non-trivial policy implications.

q-fin.GN↗
arXiv2011

Two stock options at the races: Black-Scholes forecasts

Suppose one buys two very similar stocks and is curious about how much, after some time T, one of them will contribute to the overall asset, expecting, of course, that it should be around 1/2 of the sum. Here we examine this question within the classical Black and Scholes (BS) model, focusing on the evolution of the probability density function P(w) of a random variable w = a_T^{(1)}/(a_T^{(1)} + a_T^{(2)}) where a_T^{(1)} and a_T^{(2)} are the values of two (either European- or the Asian-style) options produced by two absolutely identical BS stochastic equations. We show that within the realm of the BS model the behavior of P(w) is surprisingly different from common-sense-based expectations. For the European-style options P(w) always undergoes a transition, (when T approaches a certain threshold value), from a unimodal to a bimodal form with the most probable values being close to 0 and 1, and, strikingly, w =1/2 being the least probable value. This signifies that the symmetry between two options spontaneously breaks and just one of them completely dominates the sum. For path-dependent Asian-style options we observe the same anomalous behavior, but only for a certain range of parameters. Outside of this range, P(w) is always a bell-shaped function with a maximum at w = 1/2.

q-fin.ST↗
arXiv2010

Two-sided estimates for stock price distribution densities in jump-diffusion models

We consider uncorrelated Stein-Stein, Heston, and Hull-White models and their perturbations by compound Poisson processes with jump amplitudes distributed according to a double exponential law. Similar perturbations of the Black-Scholes model were studied by S. Kou. For perturbed stochastic volatility models, we obtain two-sided estimates for the stock price distribution density and compare the tail behavior of this density before and after perturbation. It is shown that if the value of the parameter, characterizing the right tail of the double exponential law, is small, then the stock price density in the perturbed model decays slower than the density in the original model. On the other hand, if the value of this parameter is large, then there are no significant changes in the behavior of the stock price distribution density.

q-fin.GN↗
arXiv2010

An empirical study of the tails of mutual fund size

The mutual fund industry manages about a quarter of the assets in the U.S. stock market and thus plays an important role in the U.S. economy. The question of how much control is concentrated in the hands of the largest players is best quantitatively discussed in terms of the tail behavior of the mutual fund size distribution. We study the distribution empirically and show that the tail is much better described by a log-normal than a power law, indicating less concentration than, for example, personal income. The results are highly statistically significant and are consistent across fifteen years. This contradicts a recent theory concerning the origin of the power law tails of the trading volume distribution. Based on the analysis in a companion paper, the log-normality is to be expected, and indicates that the distribution of mutual funds remains perpetually out of equilibrium.

q-fin.GN↗
arXiv2010

Boltzmann legacy and wealth distribution

We briefly review results on nonlinear kinetic equation of Boltzmann type which describe the evolution of wealth in a simple agents market. The mathematical structure of the underlying kinetic equations allows to use well-known techniques of wide use in kinetic theory of rarefied gases to obtain information on the process of relaxation to a stationary profile, as well as to identify simple interaction rules which are responsible of the formation of Pareto tails.

cond-mat.stat-mech↗
arXiv2010

On the strategic use of risk and undesirable goods in multidimensional screening

A monopolist sells goods with possibly a characteristic consumers dislike (for instance, he sells random goods to risk averse agents), which does not affect the production costs. We investigate the question whether using undesirable goods is profitable to the seller. We prove that in general this may be the case, depending on the correlation between agents types and aversion. This is due to screening effects that outperform this aversion. We analyze, in a continuous framework, both 1D and multidimensional cases.

math.OC↗
arXiv2010

Prediction accuracy and sloppiness of log-periodic functions

We show that log-periodic power-law (LPPL) functions are intrinsically very hard to fit to time series. This comes from their sloppiness, the squared residuals depending very much on some combinations of parameters and very little on other ones. The time of singularity that is supposed to give an estimate of the day of the crash belongs to the latter category. We discuss in detail why and how the fitting procedure must take into account the sloppy nature of this kind of model. We then test the reliability of LPPLs on synthetic AR(1) data replicating the Hang Seng 1987 crash and show that even this case is borderline regarding predictability of divergence time. We finally argue that current methods used to estimate a probabilistic time window for the divergence time are likely to be over-optimistic.

q-fin.ST↗
arXiv2010

The individual income distribution in Argentina in the period 2000-2009. A unique source of non stationary data

The economic crisis in Argentina around year 2002 provides a unique opportunity for Econophysics studies. The available data on individual income are analyzed to show that they correspond to non stationary states. However, the rather restricted size of the data survey imposes difficulties that must be overcome through a careful analysis, for a reliable use. A new method of data treatment is presented that could be helpful in theoretical studies.

q-fin.GN↗
arXiv2010

Business fluctuations in a credit-network economy

We model a network economy with three sectors: downstream firms, upstream firms, and banks. Agents are linked by productive and credit relationships so that the behavior of one agent influences the behavior of the others through network connections. Credit interlinkages among agents are a source of bankruptcy diffusion: in fact, failure of fulfilling debt commitments would lead to bankruptcy chains. All in all, the bankruptcy in one sector can diffuse to other sectors through linkages creating a vicious cycle and bankruptcy avalanches in the network economy. Our analysis show how the choices of credit supply by both banks and firms are interrelated. While the initial impact of monetary policy is on bank behaviour, we show the interactive play between the choices made by banks, the choices made by firms in their role as providers of credit, and the choices made by firms in their role as producers.

q-fin.GN↗
arXiv2010

Econophysics studies in Estonia

A short review of the econophysics research done in Estonia, devoted to the 15th anniversary of the term "econophysics".

q-fin.GN↗
arXiv2010

Econophysics: A new discipline

This paper debates the contribution of Econophysics to the economic or financial domains. Since the traditional approach performed by Economics or Finance has revealed to be insufficient in fully characterizing and explaining the correspondingly phenomena, we discuss whether Econophysics can provide a new insight onto these matters. Thus, an assessment is presented in order to weight its potential opportunities and limitations. This is particularly relevant as it is widely recognized that during its yet short existence Econophysics has experienced a growing interest not only by physicists but also by economists in searching for new approaches that could help explaining existing questions. In fact, many papers have been submitted, some books have been released, new journals have been published, several conferences have been held, a site is maintained -- http://www.unifr.ch/econophysics where news, events, book reviews, papers and a blog are exhibited; a 3-year licentiate studies (University of Silesia [1]) and a B.Sc. course (University of Wroclaw [2]) have been created and also some Ph.D. thesis have been written. Therefore, a fundamental question arises: Is this just a fad or is it something much more consistent that will prevail? This is what this paper addresses.

q-fin.GN↗