Identification of Interaction Effects in Survey Expectations: A Cautionary Note

A growing body of literature reports evidence of social interaction effects in survey expectations. In this note, we argue that evidence in favor of social interaction effects should be treated with caution, or could even be spurious. Utilizing a parsimonious stochastic model of expectation formation and dynamics, we show that the existing sample sizes of survey expectations are about two orders of magnitude too small to reasonably distinguish between noise and interaction effects. Moreover, we argue that the problem is compounded by the fact that highly correlated responses among agents might not be caused by interaction eects at all, but instead by model-consistent beliefs. Ultimately, these results suggest that existing survey data cannot facilitate our understanding of the process of expectations formation.Survey expectations; model-consistent beliefs; social inter- action; networks.

Diversification Patterns in the Growth of Firms: Evidence from Italian Manufacturing

We present empirical evidence on diversification patterns in Italian manufacturing firms and detect a robust relationship between firm size and diversification levels, with an elasticity of diversification that does not depend on firm size and is well below unity. Diversification does not lead to decreased corporate risk when measured in terms of the growth performance of Italian manufacturing firms. The findings support the Penrosian theory of diversification in the process of firm growth. In addition, we also speculate about the role of technology in the size-diversification nexus.

A Note on institutional hierarchy and volatility in financial markets

From a statistical point of view, the prevalence of non-Gaussian distributions in nancial returns and their volatilities shows that the Central Limit Theorem (CLT) often does not apply in nancial markets. In this paper we take the position that the independence assumption of the CLT is violated by herding tendencies among market participants, and investigate whether a generic probabilistic herding model can reproduce non-Gaussian statistics in systems with a large number of agents. It is well-known that the presence of a herding mechanism in the model is not sucient for non-Gaussian properties, which crucially depend on the details of the communication network among agents. The main contribution of this paper is to show that certain hierarchical networks, which portray the institutional structure of fund investment, warrant non-Gaussian properties for any system size and even lead to an increase in system-wide volatility. Viewed from this perspective, the mere existence of nancial institutions with socially interacting managers contributes considerably to nancial volatility.Herding; financial volatility; networks; core-perifery

Maximum Entropy Power Laws: An Application to the Tail of Wealth Distributions

tatistical equilibrium denotes the distribution of wealth that can be achieved in the largest number of ways while satisfying a first moment constraint on the rate of growth in wealth portfolios. Maximizing entropy subject to a logarithmic constraint yields a power law distribution whose characteristic exponent depends positively on the minimum wealth level, and inversely on the rate of growth and the average number of changes in the composition of wealth portfolios. Put differently, the distribution of wealth will be more unequal the faster the rate of growth in wealth and also the higher the number of turnovers.Wealth distribution, power laws, statistical equilibrium, maximum entropy.

The Small Core of the German Corporate Board Network

We consider the current bipartite graph of German corporate boards and identify a small core of directors who are highly central in the entire network while being densely connected among themselves. To identify the core, we compare the actual number of board memberships to a random benchmark, focusing on deviations from the benchmark that span several orders of magnitude. It seems that the board appointment decisions of largely capitalized companies are the driving force behind the existence of a core in Germany’s board and director network. Conditional on being a board member, it is very improbable to obtain a second membership, but multiple board membership becomes increasingly likely once this initial barrier is overcome. We also present a simple model that describes board appointment decisions as a trade-off between social capital and monitoring abilit

Identification of Interaction Effects in Survey Expectations: A Cautionary Note

A growing body of literature reports evidence of social interaction effects in survey expectations. In this note, we argue that evidence in favor of social interaction effects should be treated with caution, or could even be spurious. Utilizing a parsimonious stochastic model of expectation formation and dynamics, we show that the existing sample sizes of survey expectations are about two orders of magnitude too small to reasonably distinguish between noise and interaction effects. Moreover, we argue that the problem is compounded by the fact that highly correlated responses among agents might not be caused by interaction eects at all, but instead by model-consistent beliefs. Ultimately, these results suggest that existing survey data cannot facilitate our understanding of the process of expectations formation

A statistical equilibrium model of competitive firms

We find that the empirical density of firm profit rates, measured as returns on assets, is markedly non-Gaussian and reasonably well described by an exponential power (or Subbotin) distribution. We start from a statistical equilibrium model that leads to a stationary Subbotin density in the presence of complex interactions among competitive heterogeneous firms. To investigate the dynamics of firm profitability, we construct a diffusion process that has the Subbotin distribution as its stationary probability density. This leads to a phenomenologically inspired interpretation of variations in the shape parameter of the Subbotin distribution, which essentially measures the competitive pressure in and across industries. Our findings have profound implications both for the previous literature on the ‘persistence of profits’ as well as for understanding competition as a dynamic process. Our main formal finding is that firms' idiosyncratic efforts and the tendency for competition to equalize profit rates are two sides of the same coin, and that a ratio of these two effects ultimately determines the dispersion of the equilibrium distribution

The Real Versus the Financial Economy: A Global Tale of Stability Versus Volatility

The question how the real and the financial side of a capitalist economy relate to each other has been a frequently recurring topic in the history of economic thought. Our paper addresses this question from the viewpoint that capital ultimately seeks returns from its perpetual reallocation and essentially faces two choices: it can either be “entrepreneurially” allocated to real economic activity, or it can be “financially” invested in legal claims against such activity. Adopting such a perspective, we study here how real and financial returns relate to each other over the past fifteen years, both within and across countries, by considering more than 30,000 publicly traded firms in more than forty countries that stand for 70% of the global population and about 90% of world income. We compare the average rates of return to both types of investment and their respective volatilities. While average returns, perhaps somewhat surprisingly, turn out to be roughly equal across the two domains, the volatility of financial returns exceeds ‘real volatility’ by an order of magnitude. From a systemic point of view, these findings raise the question why capital would seek out financial investments in the first place

A spectral perspective on excess volatility

We perform a careful spectral analysis of the correlation structures observed in real and financial returns for a large pool of long-lived US corporations and find that financial returns are characterized by strong collective fluctuations that are absent from real returns. Once the excessive comovement is subtracted from individual financial time series, the behaviour of real and financial returns is virtually identical in both the cross-sectional and time series domains, thereby demonstrating the inherently collective nature of excessive fluctuations. Put differently, if excess volatility is to be reduced, then one would do well to inhibit excess comovement first. At any rate, the excessive behaviour in volatility and comovement should no longer be studied in isolation of each other

A Note on institutional hierarchy and volatility in financial markets

From a statistical point of view, the prevalence of non-Gaussian distributions in nancial returns and their volatilities shows that the Central Limit Theorem (CLT) often does not apply in nancial markets. In this paper we take the position that the independence assumption of the CLT is violated by herding tendencies among market participants, and investigate whether a generic probabilistic herding model can reproduce non-Gaussian statistics in systems with a large number of agents. It is well-known that the presence of a herding mechanism in the model is not sucient for non-Gaussian properties, which crucially depend on the details of the communication network among agents. The main contribution of this paper is to show that certain hierarchical networks, which portray the institutional structure of fund investment, warrant non-Gaussian properties for any system size and even lead to an increase in system-wide volatility. Viewed from this perspective, the mere existence of nancial institutions with socially interacting managers contributes considerably to nancial volatility