Assortative Matching, Reputation, and the Beatles Break-Up

Consider Becker's (1973) classic static matching model, with output a stochastic function of unobserved types. Assume symmetric incomplete information about types, and thus commonly observed Bayesian posteriors. Matching is then assortative in these `reputations' if expected output is supermodular in types. We instead consider a standard dynamic version of this world, and discover a robust failure of Becker's global result. We show that as the production outcomes grow, assortative matching is neither efficient nor an equilibrium for high enough discount factors. Specifically, assortative matching fails around the highest reputation agents for `low-skill concealing' technologies. Our theory implies the dynamic result that high-skill matches (like the Beatles) eventually break~up. Our results owe especially to two findings: (a) value convexity due to learning undermines match supermodularity; and (b) for a fixed policy in optimal learning, the second derivative of the value function explodes geometrically at extremes.supermodularity, convexity

Assortative Matching and Reputation

Consider Becker's classic 1963 matching model, with unobserved fixed types and stochastic publicly observed output. If types are complementary, then matching is assortative in the known Bayesian posteriors (the 'reputations'). We discover a robust failure of Becker's result in the simplest dynamic two type version of this world. Assortative matching is generally neither efficient nor an equilibrium for high discount factors. In a labor theoretic rationale, we show that assortative matching fails around the highest (lowest) reputation agents for 'low-skill (high-skill) concealing' technologies. We then find that as the number of production outcomes grows, almost all technologies are of either form. Our theory implies the dynamic result that high-skill matches eventually break up. It also reveals that the induced information rents create discontinuities in the wage profile. This in turn produces life-cycle effects: young workers are paid less than their static marginal product, and old workers more.assortative matching, incomplete information, wages, Bayesian posterior, value function

Search by Committee

We consider the problem of sequential search when the decision to stop searching is made by a committee. We show that a symmetric stationary equilibrium exists and is unique given that the distribution of rewards is log concave. Committee members set a lower acceptance threshold than do single-agent searchers. In addition, mean preserving spreads in the distribution of rewards may lower each member's continuation value | an impossibility in the single-agent setting. If committee members are very patient or very impatient, expected search duration is lower than it would be for a single agent, but, for intermediate levels of patience, this comparison may be reversed. Holding the fraction of votes required to stop fixed, expected search duration rises with committee size on patient committees but falls with committee size on impatient committees. Finally, we consider the effect of varying the number of votes required to stop, holding committee size constant. We show that the welfare-maximizing vote threshold increases in the rate of patience and that there is a finite bound on patience such that unanimity is welfare maximizing.sequential search, voting, committees

Alien Registration- Anderson, Axel (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/31271/thumbnail.jp

A Matching Model of the Housing Market: Searching for a Motivated Partner

We construct a bilateral search model of the housing market in which agents differ in their flow rewards while searching. Buyers and sellers enter the market with high flow rewards, but move at a Poisson rate to a state with low flow rewards if they do not transact in the meantime. We characterize the equilibrium steady state matching pattern and compare this to the constrained efficient matching pattern. In particular we show that equilibrium is characterized by too little /Opportunistic Matching/, in which agents with high flow values will match only with agents with low flow values. We also characterize the joint distribution of price and time to sale (for sellers). The expected price conditional on time to sale falls with time spent on the market, while the conditional variance of price first rises and then falls with time on the market.

Assortative Matching and Repubation

Consider Becker’s classic 1963 matching model, with unobserved fixed types and stochastic publicly observed output. If types are complementary, then matching is assortative in the known Bayesian posteriors (the ‘reputations’). We discover a robust failure of Becker’s result in the simplest dynamic two type version of this world. Assortative matching is generally neither efficient nor an equilibrium for high discount factors. In a labor theoretic rationale, we show that assortative matching fails around the highest (lowest) reputation agents for ‘low-skill (high-skill) concealing’ technologies. We then find that as the number of production outcomes grows, almost all technologies are of either form. Our theory implies the dynamic result that high-skill matches eventually break up. It also reveals that the induced information rents create discontinuities in the wage profile. This in turn produces life-cycle effects: young workers are paid less than their static marginal product, and old workers more

First-principles study of ferroelectric domain walls in multiferroic bismuth ferrite

We present a first-principles density functional study of the structural, electronic and magnetic properties of the ferroelectric domain walls in multiferroic BiFeO3. We find that domain walls in which the rotations of the oxygen octahedra do not change their phase when the polarization reorients are the most favorable, and of these the 109 degree domain wall centered around the BiO plane has the lowest energy. The 109 degree and 180 degree walls have a significant change in the component of their polarization perpendicular to the wall; the corresponding step in the electrostatic potential is consistent with a recent report of electrical conductivity at the domain walls. Finally, we show that changes in the Fe-O-Fe bond angles at the domain walls cause changes in the canting of the Fe magnetic moments which can enhance the local magnetization at the domain walls.Comment: 9 pages, 20 figure

Electrical microfluidic pressure gauge for elastomer microelectromechanical systems

We report on an electrical microfluidic pressure gauge. A polydimethylsiloxane microvalve closes at a characteristic applied pressure determined by the material's properties and the valve's dimensions. Hence, when the same pressure is applied to all valves of a heterogeneous valve array, some valves close while others remain open. The state of the array is combined with knowledge of the respective characteristic closing pressures of the individual valves to yield an estimate of the applied pressure. The state of each valve is obtained by electrical measurements, since the electrical resistance of the respective underlying fluid-filled channel increases by at least two orders of magnitude as the valve closes and its insulating elastomer material interrupts the electrical circuit. The overall system functions as a pressure gauge with electrical readout. This device would be a critical component in active pressure-regulation loops in future integrated microfluidic systems

Experimentally validated quantitative linear model for the device physics of elastomeric microfluidic valves

A systematic experimental study and theoretical modeling of the device physics of polydimethylsiloxane “pushdown” microfluidic valves are presented. The phase space is charted by 1587 dimension combinations and encompasses 45–295 µm lateral dimensions, 16–39 µm membrane thickness, and 1–28 psi closing pressure. Three linear models are developed and tested against the empirical data, and then combined into a fourth-power-polynomial superposition. The experimentally validated final model offers a useful quantitative prediction for a valve's properties as a function of its dimensions. Typical valves (80–150 µm width) are shown to behave like thin springs

Search by committee

We consider the problem of sequential search when the decision to stop searching is made by a committee. We show that a symmetric stationary equilibrium exists and is unique given that the distribution of rewards is log concave. Committee members set a lower acceptance threshold than do single-agent searchers. In addition, mean preserving spreads in the distribution of rewards may lower each member's continuation value - an impossibility in the single-agent setting. If committee members are very patient or very impatient, expected search duration is lower than it would be for a single agent, but, for intermediate levels of patience, this comparison may be reversed. Holding the fraction of votes required to stop fixed, expected search duration rises with committee size on patient committees but falls with committee size on impatient committees. Finally, we consider the effect of varying the number of votes required to stop, holding committee size constant. We show that the welfare-maximizing vote threshold increases in the rate of patience and that there is a finite bound on patience such that unanimity is welfare maximizing