Working papers results

We provide both an axiomatic and a neuropsychological characterization of the dependence of choice probabilities on time in the softmax (or Multinomial Logit Process) form (see below picture) MLP is the most widely used model of preference discovery in all fields of decision making, from Quantal Response Equilibrium to Discrete Choice Analysis, from Psychophysics and Neuroscience to Combinatorial Optimization. Our axiomatic characterization of softmax permits to empirically test its descriptive validity and to better understand its conceptual underpinnings as a theory of agents'rationality. Our neuropsychological foundation provides a computational model that may explain softmax emergence in human behavior and that naturally extends to multialternative choice the classical Diffusion Model paradigm of binary choice. These complementary approaches provide a complete perspective on softmaximization as a model of preference discovery, both in terms of internal (neuropsychological) causes and external (behavioral) effects.

We develop new likelihood-based methods to estimate factor-based Stochastic Discount Factors (SDF) that may accommodate Hidden Markov dynamics in the factor loadings. We use these methods to investigate whether it is possible to find a SDF that jointly prices the cross-section of eight U.S. portfolios of stocks, Treasuries, corporate bonds, and commodities. In particular, we test a range of possible different specification of the SDF, including single-state and Hidden Markov models and compare their statistical and pricing performances. In addition, we assess whether and to which extent a selection of these models replicates the observed moments of the return series, and especially correlations. We report that regime-switching models clearly outperform single-state ones both in term of statistical and pricing accuracy. However, while a four-state model is selected by the information criteria, a two-state three-factor full Vector Autoregression model outperforms the others as far as the pricing accuracy is concerned.

Deposit volatility and costly bank liquidity increase the long-term lending rates offered by banks, which reduce loan maturities, long-term investment and output. We formalise this mechanism in a banking model and analyse exogenous variation in deposit volatility induced by a Sharia levy in Pakistan. Data from the credit registry and a firm-level survey show that deposit volatility and liquidity cost: 1) reduce loan maturities and lending rates; 2) leave loan amounts and total investment unchanged; 3) redirect investment from fixed assets towards working capital. A targeted liquidity program is quantified to generate yearly output gains between 0.042% and 0.205%.

The regulation of bank liquidity can create a commitment device on repaying depositors in bad states, if deposit insurance is absent. A theoretical model shows that liquidity regulation can: 1) stimulate a deposit inflow, moderating the limited liability inefficiency; 2) promote lending and branching, if deposit growth exceeds the intermediation margin decline. Our empirical test exploits an unexpected policy change, which fostered the liquid assets of Ethiopian banks by 25% in 2011. Exploiting the cross-sectional heterogeneity in bank size and bank-level databases, we find an increase in deposits, loans and branches, with no decline in profits.

A well functioning bureaucracy can promote prosperity, as Max Weber maintained. But when bureaucracy gets jammed-a Kafkian situation-it causes stagnation. We propose a dynamic theory of the interaction between legislation and the efficiency of bureaucracy. When bureaucracy is inefficient, the effects of politicians' legislative acts are hard to assess. Incompetent politicians thus have strong incentives of passing laws to acquire the reputation of skillful reformers. But a plethora of often contradictory laws can itself lead to a collapse in bureaucratic efficiency. This interaction can spawn both Weberian and Kafkian steady states. A temporary surge in political instability, which increases the likelihood of a premature end of the legislature, exerts pressure for reforms, or results in the appointment of short-lived technocratic governments can determine a permanent shift towards the nightmare Kafkian steady state. The aggregate experience of Italy in its transition from the so-called First to the Second Republic fits the narrative of the model quite well. Using micro-data for Italian MPs, we also provide evidence consistent with the claim that when political instability is high, politicians signal their competence through legislative activism, which leads to the overproduction of laws and norms.

We define as populist a party that champions short-term protection policies while hiding their long-term costs by using anti-elite rhetoric to manipulate beliefs. We provide a framework that rationalizes this definition and generates sharp implications for people support to populist platforms (the demand side), for the timing of appear ance of populist parties and their chosen orientation (the supply side) as well as for non-populist parties response to populist success (an equilibrium market reaction). Using individual data on voting in European countries we document that key fea tures of the demand for populism as well as the supply heavily depend on turnout incentives, previously neglected in the populism literature. Once turnout effects are properly taken into account, economic insecurity drives consensus to populist policies directly as well as through indirect negative effects on trust and attitudes towards migrants. On the supply side, populist parties are more likely to emerge and prosper when countries deal with systemic economic insecurity crisis that both left-oriented incumbent parties (relying on government-based policies) and right-oriented (relying on markets) find hard to address, disappointing voters who lose faith in them and abstain. Relative entry space determines the orientation choice of populist parties, i.e., whether they enter on left or right of the political spectrum. The typical non-populist party policy response is to reduce the distance of their platform from that of new populist entrants, thereby magnifying the aggregate supply of populist policies.

This paper proposes an integrated simple theory of bargaining and conflict between ethnic groups, delivering novel predictions on secessionist versus centrist conflict, and confronting them to the data. We find that greater size of the opposition ethnic groups reduces the likelihood of peaceful union with respect to secessionist and centrist conflict, and that cultural preference similarity decreases the risk of secessionist conflict with respect to centrist conflict and with respect to union. Finally, we show that greater patience increases the likelihood of secessionist conflict with respect to centrist conflict.

Creativity is often highly concentrated in time and space, and across different domains.
What explains the formation and decay of clusters of creativity? We match data on notable
individuals born in Europe between the XIth and the XIXth century with historical city data.
The production and attraction of creative talent is associated with city institutions that protected economic and political freedoms and promoted local autonomy. Instead, indicators of local economic conditions such as city size and real wages, do not predict creative clusters. We also show that famous creatives are spatially concentrated and clustered across disciplines, that their spatial mobility has remained stable over the centuries, and that creative clusters are persistent but less than population.

We consider a game with sequential moves played by agents who are randomly drawn from large populations and matched. We assume that, when players are uncertain about the strategy distributions of the opponents, preferences over actions at any information set admit a smooth-ambiguity representation in the sense of Klibanoff, Marinacci, and Mukerji (Econometrica, 2005). This may induce dynamically inconsis- tent preferences and calls for an appropriate definition of sequential best response. We take this into account in our analysis of self-confirming equilibrium (SCE) and rationalizable SCE in sequential games with feedback played by agents with non-neutral ambiguity attitudes. Battigalli, Cerreia-Vioglio, Maccheroni, and Marinacci (Amer. Econ. Rev., 2015) show that the set of SCE's of a simultaneous-move game with feedback expands as ambiguity aversion increases. We show by example that SCE in a sequential game is not equivalent to SCE applied to the strategic form of such game, and that the previous monotonicity result does not extend to general sequential games. Still, we provide sufficient conditions under which the monotonicity result holds for (rationalizable) SCE.

The Wold decomposition of a weakly stationary time series extends to the multivariate case by allowing each entry of a weakly stationary vectorial process to linearly depend on the components of a vector of shocks. Since univariate coefficients are replaced by matrices, we propose a modelling approach based on Hilbert A-modules defined over the algebra of squared matrices. The Abstract Wold Theorem for Hilbert A-modules, that we prove, delivers two orthogonal decompositions of vectorial processes: the Multivariate Classical Wold Decomposition, which exploits the lag operator as isometry, and the Multivariate Extended Wold Decomposition, where a scaling operator is employed. The latter enables us to disentangle the heterogeneous levels of persistence of a weakly stationary vectorial process. Hence, the persistent components of the macro-financial variables into consideration are related to the overlapping of different sources of randomness with specific persistence. We finally provide a simple application to V AR models.