On the Importance of Frailty in Social Science Theory (and other lessons of agent-based modeling)

This paper is about the theoretical implications of agent-based modeling exercises. Construction of an agent-based model challenges a social scientist to formalize many concepts and relationships that would have remained implicit or unrecognized. While formalizing these "unimportant" assumptions can be a nuisance, it can also have substantial theoretical payoffs. In order to fill the gaps of the model, the researcher is forced to confront the gaps in the theory that motivated the model in the first place. Using examples drawn from several large political science simulation models, the paper argues that frailty, defined as unpredictability in the behavior of agents, is often required in order to bring closure to the modeling exercise. It is difficult (or impossible) to square the dynamic or aggregate implications of the agent-based model with observations without placing a substantial amount of emphasis on frailty. Hence, the component in behavior that we often treat as "error" in empirical analysis is actually a vital part of the glue that makes the many different moving parts of a social system interact in coherent ways. The example models were developed with the Swarm simulation system (http://www.swarm.org) during the last decade

Binary Classification of Wind Fields through Hypothesis testing on Scatterometer Measurements

Scatterometers are radars specially designed to nearsurface wind over the ocean from space. Traditional scatterometer wind estimation inverts the model function relationship between the wind and backscatter at each resolution element, yielding a set of ambiguities due to the many-to-one mapping of the model function. Field-wise wind estimation dramatically reduces the number of ambiguities by estimating the wind at many resolution elements, simultaneously, using a wind model that constrains the spatial variability of the wind. However, the appropriate choice of the model order needed for a particular wind field is not known a priori. The approximate model order is valuable because of the implicit trade-off between the computational complexity of high-order models and the imprecise model fit of low-order models. In this paper, a simple binary classification of wind fields is proposed which identifies whether or not a region will be well modeled by a low-order wind model. The raw scatterometer measurements provide data about the wind that can be exploited through hypothesis testing to identify the appropriate model order to use in field-wise wind estimation. Improved processing algorithms lead to better use of the data

PROCESS MODELS OF EXPERTISE FOR DECISION MAKING

Information processing models of expertise in problem solving and decision making are not new. Indeed, one of the major results of the study of complex tasks over the past twenty years is that expertise consists of large amounts of task/domain-specific knowledge, arguably in the form of patterns or rules (the 50,000 patterns hypothesis). In this tutorial, an alternative that arises in environments where there is little or no opportunity for large numbers of patterns to develop will be presented. Two examples will be considered. The first example is the problem of fraud detection in auditing, where the base rate of occurrence of the phenomenon is low and most auditors have little or no direct experience. Despite this lack of experience, there are auditors who are quite successful in detecting frauds in simulated versions of real fraud cases. The second example is the diagnosis of faults in a manufacturing line in semi-conductor (VLSI) fabrication. In this setting there is also limited opportunity for patterns to develop, due to the problem of obsolete knowledge caused by the rapid changes in device and process designs. Once again, however, there are typically a small number of individuals who are successful in performing this task. The question we shall consider in this tutorial is how to explain success under these circumstances

Design of test specimens and procedures for generating material properties of Douglas fir/epoxy laminated wood composite material: With the generation of baseline data at two environmental conditions

In support of the design of wind turbine generator airfoils/blades utilizing Douglas Fir/West System Epoxy laminated composite material, a program was undertaken to define pertinent material properties utilizing small scale test specimens. Task 1 was the development of suitable monotonic tension, compression, short beam shear and full reversed cyclic specimen designs and the companion grips and testing procedures. Task 2 was the generation of the material properties at two environmental conditions utilizing the specimens and procedures developed in Task 1. The monotonic specimens and procedures generated results which compare favorably with other investigators while the cyclic results appear somewhat conservative. Adding moisture and heat or scarf joints degraded the monotonic performance but had a more nebulus effect with cyclic loading

Ethical Leadership in the Age of Apology

The growing importance of public apology makes forgiveness seeking a critical responsibility for ethical leaders. Leaders must offer apologies on behalf of themselves (in their roles as moral people) and on behalf of the organizations they lead (in their roles as moral managers). Morally satisfying apologies adequately acknowledge offenses, express remorse, offer explanations, and make reparations for damages. The apologies of disgraced professional cyclist Lance Armstrong and General Motors CEO Mary Barra demonstrate how incomplete apologies can undermine ethical leadership. Armstrong’s apology did little to atone for his failings as a moral person. In her role as a moral manager, Barra did not fully account for GM’s cover-up of a defective, fatal switch problem or demonstrate enough concern for victims and the public. The shortcomings of these forgiveness-seeking acts demonstrate the importance of providing a complete accounting, matching the depth of the apology to the depth of the wrongdoing, following through on commitments, and carefully choosing the venue for delivering an apology

Probability of Attack by Southern Pine Beetle in Relation to Distance from an Attractive Host Tree

The pattern of southern pine beetle (SPB) attack was examined in two infestations in East Texas to determine the probability of host tree attack (PA) as a function of distance (X) from a recently attacked tree (pheromone source). In an infestation having a low rate of newly attacked trees per day and only a few pheromone sources occurring simultaneously, distance was a critical factor in determining PA. The probability decreased as In X, and was described by the regression model, PA=0.06757- 0.2583 In X. Distance, however, was less critical in a larger infestation which had multiple pheromone sources occurring simultaneously and a high rate of new trees attacked each day. Implications for pheromone control strategies utilizing SPB attractants are discussed. FOREST SCL 24:574-580

Characterizing Flight Aggregation of the Southern Pine Beetle

Spatial aggregation patterns of flying southern pine beetles, Dendroctonus frontalis Zimm., were studied using a systematic grid of sticky flight traps placed in 3 beetle infestations. Five methods of characterizing dispersion were compared: Lloyd\u27s index of patchiness (IP), Morisita\u27s index of dispersion (15), the coefficient of dispersion (CD), the slope of Taylor\u27s power function (b) and the slope of Iwao\u27s regression of mean crowding on mean density (m). All indices indicated a high degree of aggregation of flying southern pine beetles within the infestations. The indices varied, however, in their ranking of aggregation for the 3 study sites. IP and 15 gave the same relative results while CD showed a different pattern. The two regression techniques showed no significant differences between slopes for the various study sites. The m-m regression provided more information for interpretation and more potential for evaluating influences of system manipulations. It is recommended, therefore, for characterization of southern pine beetle aggregation within infestations. IP (which serves as the theoretical basis of the regression), is suggested for comparisons between daily aggregation patterns. The m-m regression may be useful for evaluating behavioral chemical effects on aggregation through comparison of daily m-m pairs to the 95% prediction limits about the regression line; pairs falling outside these limits represent aggregation patterns significantly different from the norm

Consumption inequality and income uncertainty

This paper places the debate over using consumption or income in studies of inequality growth in a formal intertemporal setting. It highlights the importance of permanent and transitory income uncertainty in the evaluation of growth in consumption inequality. We derive conditions under which the growth of variances and covariances of income and consumption can be used to separately identify the growth in the variance of permanent and transitory income shocks. Household data from Britain for the period 1968-1992 are used to show a strong growth in transitory inequality toward the end of this period, while younger cohorts are shown to face significantly higher levels of permanent inequality