Structural shifts in urban population density gradients: an empirical investigation

This study investigates the structural shifts in urban population density gradients by first using the shifting regression technique of Farley, Hinich, and McGuire to detect the possible change in the structure of an urban area. Secondly, a generalized random coefficient technique is used to simultaneously detect the possible structural change and stochastic behavior of density gradients. Data for 50 United States SMSA's are used to do the empirical analyses.     

Contributions to nonparametric generalized failure rate function estimation

For a specified distribution functionG with densityg, and unknown distribution functionF with densityf, the generalized failure rate function (x)=f(x)/gG ^–1 F(x) may be estimated by replacingf andF byf _n and , wheref _n is an empirical density function based on a sample of sizen from the distribution functionF, and . Under regularity conditions we show and, under additional restrictions whereC is a subset ofR and _n. Moreover, asymptotic normality is derived and the Berry-Esséen type bound is shown to be related to a theorem which concerns the sum of i.i.d. random variables. The order boundO(n^–1/2+c _n ^1/2 ) is established under mild conditions, wherec _n is a sequence of positive constants related tof _n and tending to 0 asn.Research was supported in part by the Army, Navy and Air Force under Office of Naval Research contract No. N00014-76-C-0608. AMS 1970 subject classifications. Primary 62G05. Secondary 60F15.     

Zur Frage der Produktionsplanung mit der Anwendung mathematischer Methoden in der Serienfertigung

Ohne Zusammenfassung     

OR vice: Forecasting and classification techniques for narcotics interdiction

Counternarcotics interdiction efforts have traditionally relied on historically determined sorting criteria or “best guess” to find and classify suspected smuggling traffic. We present a more quantitative approach which incorporates customized database applications, graphics software and statistical modeling techniques to develop forecasting and classification models. Preliminary results show that statistical methodology can improve interdiction rates and reduce forecast error. The idea of predictive modeling is thus gaining support in the counterdrug community. The problem is divided into sea, air and land forecasting, only part of which will be addressed here. The maritime problem is solved using multiple regression in lieu of multivariate time series. This model predicts illegal boat counts by behavior and geographic region. We developed support software to present the forecasts and to automate the process of performing periodic model updates. During the period, the model was in use at. Coast Guard Headquarters. Because of deterrence provided by improved intervention, the vessel seizure rate declined from 1 every 36 hours to 1 every 6 months. Due in part to the success of the sea model, the maritime movement of marijuana has ceased to be a major threat. The air problem is more complex, and required us to locally design data collection and display software. Intelligence analysts are using a customized relational database application with a map overlay to perform visual pattern recognition of smuggling routes. We are solving the modeling portion of the air problem using multiple regression for regional forecasts of traffic density, and discriminant analysis to develop tactical models that classify “good guys” and “bad guys”. The air models are still under development, but we discuss some modeling considerations and preliminary results. The land problem is even more difficult, and data collection is still in progress.     

Maximizing purchase decision factors other than price

Assessing and acquiring technology does not have to be chaotic, driven solely by price, clinical preference, and emotion. With the tools available, it can be distilled to a process of organized common sense, which results in maximum flexibility for the user and allows materiel managers to procure the best, most cost-effective equipment for the hospital.     

On randomization, modeling and experimental design; a new example in an old discussion

Fisher and "Student" quarreled in the early days of statistics about the design of experiments, meant to measure the difference in yield between to breeds of corn. This discussion comes down to randomization versus model building. More than half a century has passed since, but the different views remain. In this paper the discussion is put in terms of artificial randomization and natural randomization, the latter being what remains after appropriate modeling. Also the Bayesian position is discussed. An example in terms of the old corn-breeding discussion is given, showing that a simple robust model may lead to inference and experimental design that outperforms the inference from randomized experiments by far. Finally similar possibilities are suggested in statistical auditing.     

Comparing the resource‐based and relational views: knowledge transfer and spillover in vertical alliances

We compare resource‐based and relational perspectives to examine competitive advantages within the context of vertical learning alliances. Previous research has shown that through such alliances suppliers acquire knowledge to forge new capabilities and attain performance improvements. We ask whether such improvements are exclusive to the learning partnership, or are available in other average partnerships of this supplier. We posit that the extent to which such performance improvements are partnership exclusive depends on whether the newly forged capabilities lie entirely within the supplier firm's boundaries, or at the learning dyad level. As such, we untie two forms of performance improvements arising from learning dyads. While the resource‐based view helps explain the performance gains learning suppliers deploy across average partners, the relational view reveals the additional performance edge that remains exclusive to the learning partnership. Based on empirical evidence from a survey of 253 suppliers to the equipment industry, we find that partnership exclusive performance (i.e., ‘relational performance’), the true source of learning dyads' competitive advantage, is a function of suppliers acquiring know‐how within the dyad, developing dyad‐specific assets and capabilities, and structuring buyer‐supplier relational governance mechanisms. We discuss implications for research and practice. Copyright © 2008 John Wiley & Sons, Ltd.