Giovanni Paolo Crespi

Propensity to invest in stocks is highly heterogeneous, with many households avoiding stock market participation altogether. This heterogeneity is difficult to reconcile with standard economic theory. We study the role of memories in shaping investment decisions and in influencing how individuals incorporate stock-related information. Across two experiments, participants invest in a stock and are compensated based on its actual price realization. In the first experiment, we verify that activating memories prior to investing systematically shifts investment behavior. Participants asked to recall stock market–related memories before the investment task make more polarized choices: recalling positive memories increases investment relative to recalling non-positive ones, while activating non-positive memories lowers investment compared with not activating them. The second experiment reveals our central finding: the effect of information critically depends on the type of memory activated. All participants recall a memory before investing, after which some receive positive and truthful information about the stock. Information meaningfully increases investment only among participants who recalled non-personal memories; in contrast, recalling personal memories completely eliminates the response to information. We show that this sharp interaction cannot be explained by changes in beliefs, overconfidence, or mistrust in experts. Instead, it can be rationalized within a selective memory framework.

Catastrophic events, which are becoming increasingly frequent due to climate change, have significant negative impacts on housing. Yet, decision-makers remain puzzled by the low uptake rates for insurance coverage against these events. In this paper, we investigate whether this phenomenon is driven by individuals having miscalibrated beliefs about the likelihood of such events occurring. Additionally, we examine the impact of an information treatment designed to correct these perceived probabilities. Our experimental results show that participants in the treatment respond as expected, adjusting their beliefs accordingly. Moreover, these belief shifts influence participants’ demand for information on the topic and their interest in purchasing insurance. However, a follow-up survey conducted two months after the main experiment reveals that the effects of the treatment are short-lived, dissipating entirely within this period. Moreover, the information treatment shifts estimates about past mortality due to circulatory diseases, which are not closely related to the content of the information treatment, although more modestly. These two insights suggest ways of improving survey design in the field of information provision experiments. Our overall findings provide important insights for policymakers, highlighting the transient nature of the treatment-induced effects.

In un panorama economico sempre più frammentato e complesso, come si definisce e come si misura oggi il valore? Il volume raccoglie contributi scientifici e riflessioni maturate dal dialogo tra il mondo accademico, l'istat e le istituzioni, mettendo in luce la duplice dimensione della crescita: quella globale, legata alle grandi dinamiche dei mercati, e quella locale, profondamente radicata nei territori. Ne emerge una lettura integrata della ricchezza delle nazioni come fenomeno complesso e multidimensionale. La ricchezza non si esaurisce nei flussi economici correnti, ma prende forma nella capacità di governare risorse strategiche, costruire reti produttive resilienti, accumulare patrimonio nel tempo e adattarsi a un contesto globale in continuo mutamento. Il volume rafforza così la consapevolezza che ricchezza, competitività e resilienza delle economie dipendono da un intreccio sempre più stretto tra risorse materiali, strutture produttive, relazioni internazionali, capacità di accumulazione e qualità delle reti d'impresa.

In this paper, we provide a systematization of the equilibrium concepts for vector-valued games. In general abstract setting, we give the definitions of Nash equilibrium, weak Nash equilibrium, and proper Nash equilibrium, we investigate the relationships among them, and we provide existence results for proper Nash equilibria and weak Nash equilibria. The link between the introduced equilibrium concepts and Nash equilibria of a game with scalar payoffs obtained by means of linear scalarization is investigated. For a vector matrix game, we show that the notions of proper Nash equilibrium and Nash equilibrium are equivalent, we prove existence of both Nash equilibria and weak Nash equilibria, we give characterizations of proper and weak best correspondence sets respectively, by defining characterizing functions from the matrices and the preference cones, and finally we list all best correspondence sets. The given definitions are illustrated by means of examples.

A robust game is a distribution-free model to handle ambiguity generated by a bounded set of possible realizations of the values of players' payoff functions. The players are worst-case optimizers and a solution, called robust-optimization equilibrium, is guaranteed by standard regularity conditions. The paper investigates the sensitivity to the level of uncertainty of this equilibrium focusing on robust games with no private information. Specifically, we prove that a robust-optimization equilibrium is an epsilon-Nash equilibrium of the nominal counterpart game, where epsilon measures the extra profit that a player would obtain by reducing his level of uncertainty. Moreover, given an epsilon-Nash equilibrium of a nominal game, we prove that it is always possible to introduce uncertainty such that the epsilon-Nash equilibrium is a robust-optimization equilibrium. These theoretical insights increase our understanding on how uncertainty impacts on the solutions of a robust game. Solutions that can be extremely sensitive to the level of uncertainty as the worst-case approach introduces non-linearity in the payoff functions. An example shows that a robust Cournot duopoly model can admit multiple and asymmetric robust-optimization equilibria despite only a symmetric Nash equilibrium exists for the nominal counterpart game.

Via a family of monotone scalar functions, a preorder on a set is extended to its power set and then used to construct a hull operator and a corresponding complete lattice of sets. Functions mapping into the preordered set are extended to complete lattice-valued ones, and concepts for exact and approximate solutions for corresponding set optimization problems are introduced and existence results are given. Well-posedness for complete lattice-valued problems is introduced and characterized. The new approach is compared with existing ones in vector and set optimization. Its relevance is shown by means of many examples from multicriteria decision making, statistics, and mathematical economics and finance.

Set-valued extensions of vector-valued functions are used to investigate the relations between weak efficiency and variational inequalities (both Stampacchia and Minty type) which allows to apply the complete lattice framework from set optimization. Since the seminal work of Giannessi, it has been a challenge to generalize scalar results to the vector case. In this effort, some notions of generalized derivatives for vector-valued functions have been introduced, either in the form of set-valued functions or introducing appropriate notions of infinite elements in vector spaces. Switching the focus to set optimization in conlinear spaces, we propose a Dini-type derivative, that keeps the same set-valued form of the optimization problem.