Heterogeneous adaptive expectations and cobweb phenomena

We study a cobweb-type commodity market where n firms operate and characterised by a strictly monotone demand and supply. The firms are assumed to differ in a key parameter governing price expectations which we suppose to be adaptive. We characterise the unique steady state of the resulting economic dynamics in terms of stability and we study the impact of the number and diversity of firms: to this end we introduce the notions of structural and behavioural degree of instability which prove to be crucial in determining whether stability or instability prevail. We also consider the case of market merging and establish conditions to have stability (or instability) in the aggregated market in terms of the original (structural and behavioural) degrees of instability. We take up the issue of transitional dynamics and speed of convergence when the system is stable and characterise parametric configurations that maximise the speed of convergence. Motivated by the difficulty to actually observe expectations, whereas it is easier to measure some structural features of a given market, such as the relevant demand and supply price elasticities, we take the perspective of an observer (e.g. a policy maker) whose information set includes the structural but not the behavioural degree of instability. We therefore assume the firms - via the parameter which defines their expectations - are sampled independently from a population described by a given probability distribution. In this case the structural degree of instability determines how the number of potentially different firms affects the probability of ending up with a stable outcome. Analytical results are provided alongside numerical evidence.heterogeneous agents, expectations, stability of steady states, market merging, speed of convergence

Dynamics in Non-Binding Procurement Auctions with Boundedly Rational Bidders

We study a procurement auction recently analysed by Gal-Or et al. (2007). In this auction game the buyer ranks different bids on the basis of both the prices submitted and the quality of each bidder that is her private information. We emphasise the similarity between this model and existing models of competition in horizontally differentiated markets. Finally we illustrate conditions for the existence and the stability of such equilibrium. To this end we extend the model to a dynamic setting in which a sequence of independent auctions takes place. We assume bidders have bounded rationality in a twofold sense. On one hand, they use an underparametrized model of their competitors’ behaviour, best responding to expectations on average bids rather than keeping track of the entire vector of competitors’ bids. On the other they update expectations adaptively. In a general framework with more than two bidders the system may fail to converge to the steady state, i.e. to the symmetric Nash equilibrium of the original game.Non-binding auctions, Product differentiation, Hotelling Duopoly, Expectations, Stability of steady states

Information Disclosure in Procurement Auctions with Horizontally Differentiated Suppliers

This work studies a model of multidimensional auction in which a buyer needs to procure a given good from either of two potential suppliers whose quality is the buyer's private information and whose production costs are heterogeneous. Costs asymmetries constitute a novelty in this framework and extend e.g. the model of Gal-Or et al. (2007). We compare the outcomes of different procurement policies from the viewpoint of both efficiency and the buyer's payoff. A trade-off between efficiency and rent-extraction emerges. The buyer will maximize her expected utility by selecting a first score auction and either concealing or privately revealing suppliers'quality - the optimal choice depending on the degree of heterogeneity in suppliers' costs and qualities. However, neither of these auction mechanisms will be efficient: efficiency calls for a second score auction or a first score auction with public disclosure of suppliersquality. The findings hinge on the equivalence between auction models and models of horizontal differentiation and take advantage of results for asymmetric auctions developed by Maskin & Riley (2000).multidimensional auctions, procurement policies, endogenous information, horizontal di¤erentiation, asymmetric auctions.

Endowment effects at different time scenarios: the role of ownership and possession

The central issue of the wide literature about the endowment effect is the search for an explanation of the fact that the selling price of a good will be higher than that at which a person is willing to buy that same good, once they own it. The experimental evidence is not unanimous in replicating the results found by Kahneman et al. (1990 and 1991). The challenge is that of disentangling the several determinants that may be at work in generating the final effect, as the loss aversion is not considered the only explanation. We dig deeper by examining two of these likely determinants which remain understudied: the first is the impact that the amount of time of ownership can have on the endowment effect. The second is the type of item (non-material good and exchange goods) used to test the effect. Through an online questionnaire we investigate these aspects by using three different goods: a mug, an Amazon Gift Card and a quarterly subscription to Spotify. We also test whether the endowment effect occurs in different time scenarios, that is if participants imagine to own the good for one day, one week or one month. We find that the endowment effect clearly appears for all types of goods while less clear results take shape when considering the duration of the ownership

micro-LIBS vs. XRF analysis of surface-enriched silver coins. Is a micro-destructive approach really unavoidable?

We have performed a comparative study of micro-LIBS and X-Ray Fluorescence Spectroscopy (XRF) analysis for quantifying the silver contents in Swabian deniers minted during the Kingdom of Sicily (1194-1266). The combined use of the two techniques allowed us to validate the chemical composition of the coins and to valuate the altered surface and the surface-enrichment treatment eventually undergone. The use of LIBS coupled with microscope allowed to reduce the dimen- sion of the laser-induced crater below 20μm so the visual aspect of the coin remains unchanged. The LIBS measures over- come the question of the surface alteration, but they do not represent the heterogeneity of the alloy because of the small sampling area. On the other hand, the XRF technique allows to analyze a larger surface, in a totally non destructive way; however, the sampling volume could be affected by alterations or excessive roughness. It has been verified that these two factors do not affect the reliability of the measures but could introduce an uncertainty in the quantity data. The LIBS quanti- tative data have been obtained using the One Point Calibration method (OPC) while the XRF quantitative data were ob- tained by means of the Fundamental Parameter method. A good agreement between the two results was found, demonstrat- ing the effectiveness of both the micro-LIBS and XRF techniques, in spite of the above mentioned limitations. The compara- tive study has been conducted on a group of 50 deniers belonging to the reign of Henry VI and Frederick II; the results con- firmed the knowledge about the devaluations of the coins within 50 years of the Swabian Kingdom. A classification method has been proposed to set historically the coins