Showing papers on "Matching (statistics) published in 1986"

Statistical Matching Using File Concatenation With Adjusted Weights and Multiple Imputations

Abstract: Statistically matched files are created in an attempt to solve the practical problem that exists when no single file has the full set of variables needed for drawing important inferences. Previous methods of file matching are reviewed, and the method of file concatenation with adjusted weights and multiple imputations is described and illustrated on an artificial example. A major benefit of this approach is the ability to display sensitivity of inference to untestable assumptions being made when creating the matched file.

Wages and Job Mobility of Young Workers

Abstract: This paper presents a discrete-time version of Jovanovic's model of worker-firm matching. Descriptive evidence is presented that supports the notion that unobserved worker-firm heterogeneity is an important component in the intertemporal structure of wages for young workers. A structural econometric model of wage dynamics under worker-firm sorting is developed and estimated. Finally, a formal test of the matching model is carried out, and the matching structure on intertemporal covariances of wages is not rejected. My results indicate the necessity of jointly considering processes of turnover and wage growth when analyzing the labor market experiences of young workers.

NP-completeness of the set unification and matching problems

Abstract: The set-unification and set-matching problems, which are very restricted cases of the associative-commutative-idempotent unification and matching problems, respectively, are shown to be NP-complete. The NP-completeness of the subsumption check in first-order resolution follows from these results. It is also shown that commutative-idempotent matching and associative-idempotent matching are NP-hard, thus implying that the idempotency of a function does not help in reducing the complexity of matching and unification problems.

The matching law applies to wagtails' foraging in the wild.

Abstract: Field data concerning the time budgets and foraging success of pied wagtails (Motacilla alba yarrelli, Gould) are reanalyzed. It is found that the data are well described by the generalized matching law, with a marked bias towards spending time on the territory. In this case matching is not the result of maximizing reward rate, but it remains possible that it results from an allocation of time that maximizes survival.

Matching patients with treatments: conceptual and methodological issues.

Abstract: The current enthusiasm for matching patients with optimal treatments rests on limited conceptual analyses In addition, much of the existing research on patient-treatment matching has been based on methodological assumptions that are not commensurate with the complexity of the matching problem Six key conceptual and methodological issues that underlie attempts to match patients with optimal forms of treatment and to conduct research on patient-treatment matching are outlined The conceptual issues are: selecting effective matching variables, specifying the end result that matching is to enhance and determining the stage(s) in the treatment process at which matching decisions are to be made The three methodological issues deal with the type of patient-treatment match or interaction effect and include: nonlinear interaction effects, higher-order interaction effects and multilevel interaction effects Examples clarifying these issues are drawn from the literature on treating alcohol-dependent persons, but

An adaptive planner

Abstract: This paper is about an approach to the flexible utilization of old plans called adaptive planning. An adaptive planner can take advantage of the details associated with specific plans, while still maintaining the flexibility of a planner that works from general plans. Key elements in the theory of adaptive planning are its treatment of background knowledge and the introduction of a notion of planning by situation matching.

Tight bounds for minimax grid matching, with applications to the average case analysis of algorithms

Abstract: The minimax grid matching problem is a fundamental combinatorial problem associated with the average case analysis of algorithms. The problem has arisen in a number of interesting and seemingly unrelated areas, including wafer-scale integration of systolic arrays, two-dimensional discrepancy problems, and testing pseudorandom number generators. However, the minimax grid matching problem is best known for its application to the maximum up-right matching problem. The maximum up-right matching problem was originally defined by Karp, Luby and Marchetti-Spaccamela in association with algorithms for 2-dimensional bin packing. More recently, the up-right matching problem has arisen in the average case analysis of on-line algorithms for 1-dimen-sional bin packing and dynamic allocation.

A stochastic approach to stereo vision

Abstract: A stochastic optimization approach to stereo matching is presented. Unlike conventional correlation matching and feature matching, the approach provides a dense array of disparities, eliminating the need for interpolation. First, the stereo matching problem is defined in terms of finding a disparity map that satisfies two competing constraints: (1) matched points should have similar image intensity, and (2) the disparity map should be smooth. These constraints are expressed in an "energy" function that can be evaluated locally. A simulated annealing algorithm is used to find a disparity map that has very low energy (i.e., in which both constraints have simultaneously been approximately satisfied). Annealing allows the large-scale structure of the disparity map to emerge at higher temperatures, and avoids the problem of converging too quickly on a local minimum. Results are shown for a sparse random-dot stereogram, a vertical aerial stereogram (shown in comparison to ground truth), and an oblique ground-level scene with occlusion boundaries.

Matched case-control designs and overmatched analyses

Abstract: In a 1:1 matched-pairs case-control study, several pairs may have the same matching criteria. The objective of this paper is to consider various analytic approaches for odds ratio estimation in this situation. One approach is to perform the usual matched-pairs analysis; the alternative is to combine pairs into strata and compute the conditional maximum likelihood or Mantel-Haenszel estimate. Matched-pairs analysis based on theoretic and simulation results may give misleading inferences, although on average it performs nearly as well as the stratified analysis. The occasional poor performance of the matched-pairs analysis results from the possibility of obtaining an extreme number of discordant pairs due to the random pairing within a stratum. It is concluded that the prudent policy is to perform a stratified rather than a paired analysis, even at the expense of additional computation.

Matching behavior and collective action: Some experimental evidence

Abstract: A new approach to explaining voluntary collective action, emphasizing strategic interactions of actors in their contributions to the provision of a public good, is tested experimentally. The results support this approach, and tend to reject the conventional, Cournot theory of the provision of public goods. Among the findings are a positive interaction between individual contributions to the provision of a public good, and a U-shaped time trend in combined contributions.

Photogrammetric standard methods and digital image matching techniques for high precision surface measurements

Abstract: Photogrammetry is a flexible 3D-measuring technique based on images of the object. Its relative precision, ranging from 1:30 000 to 1:300 000, is due to the high quality of the hardware and the simultaneous treatment of all geometric information in a joint least squares estimation. The interactive measuring process allows a stepwise integration of algorithms from pattern recognition to support or replace manual tasks. A new image matching procedure has been developed and implemented on an analytical measuring device for high precision surface measurements. The paper discusses the methodology of analytical photogrammetry, the theoretical accuracy of stereopsy and the features of the image matching system.

Selection of Single Sampling Plans for Variables Matching the MIL-STD-105 Scheme

Abstract: Tables are given for the selection of single sampling plans for variables using three forms of acceptance criteria (sigma-method, s-method and R-method) which match the Operating Characteristic performance of MIL-STD-105D plans These matched plans are

Hierarchical matching using relaxation

Abstract: In this paper we outline the application of a general relaxation-based matching procedure to the problem of matching pairs of images and discuss the extension of the basic technique to matching hierarchical descriptions of scenes.

On the complexity of stable matchings with and without ties

Abstract: This thesis concerns the complexity analysis of certain matching problems. The description of each of these matching problems consists of a group of agents, and, for each agent, a preference list over the agents with whom the agent can be matched. A solution to the problem is a matching that has the property that no pair of agents that are eligible for each other, prefer each other to their assigned mates. A matching that satisfies this property is called a stable matching. The variants of this problem that will be dealt with are: (1) The marriage problem: matching of men and women into couples; (2) The roommate problem: matching of students into rooms of two occupants; (3) The intern assignment problem: the assignment of interns to hospital positions; (4) The intern assignment problem with couples: same problem as (3) except that some of the interns are married couples. These matching problems can be defined to allow or disallow ties in the preference lists. When ties are allowed, stability is defined as the absence of an unmatched pair that strictly prefer each other to their assigned mates. This thesis will show that the option of allowing ties in the preference lists can significantly affect the computational complexity of the problems. It will be shown that, when ties are allowed, the roommate problem and the intern assignment problem with couples are NP-complete. In contrast, the roommate problem without ties, is solvable in polynomial time. The computational complexity of the intern-hospital assignment problem with couples is unresolved. A variant of the marriage problem that allows ties will be shown to be logspace P-complete. Finally, the intern-hospital assignment problem with couples, but without ties, will be shown to be logspace P-hard.

Human capital, job matching and earnings growth between jobs: an empirical analysis

Abstract: The process of job matching is complementary to human capital investment in determining earnings growth over the individual job history. Change in earnings associated with moving between jobs is portrayed as a result of matching. In this paper the idea of job matching is refined to distinguish between job matching within firms and job matching across firms. The derived hypotheses are supported by empirical results of a causal model which controls for human capital and personal endowment variables.

Signal matching through scale space

Abstract: Given a collection of similar signals that have been deformed with respect to each other, the general signal matching problem is to recover the deformation. We formulate the problem as the minimization of an energy measure that combines a smoothness term and a similarity term. The minimization reduces to a dynamic system governed by a set of coupled, first-order differential equations. The dynamic system finds an optimal solution at a coarse scale and then tracks it continuously to a fine scale. Among the major themes in recent work on visual signal matching have been the notions of matching as constrained optimization, of variational surface reconstruction, and of coarse-to-fine matching. Our solution captures these in a precise, succinct, and unified form. Results are presented for one-dimensional signals, a motion sequence, and a stereo pair.

The Dedicated Bond Portfolio in Pension Funds—Part II: Immunization, Horizon Matching and Contingent Procedures

Abstract: (1986). The Dedicated Bond Portfolio in Pension Funds—Part II: Immunization, Horizon Matching and Contingent Procedures. Financial Analysts Journal: Vol. 42, No. 2, pp. 47-57.

Computing Stereopsis Using Feature Point Contour Matching

Abstract: Computational models of the human stereo system can provide insight into general information processing constraints that apply to any stereo system, either artificial or biological. In 1977, Marr and Poggio proposed one such computational model, that was characterized as matching certain feature points in difference-of-Gaussian filtered images, and using the information obtained by matching coarser resolution representations to restrict the search space for matching finer resolution representations. An implementation of the algorithm and its testing on a range of images was reported in 1980. Recent computational experiments applying the algorithm to a variety of natural images, especially aerial photographs, have led to a number of modifications. In this article, we present a version of the Marr-Poggio-Grimson algorithm that embodies these modifications, and is characterized as matching extended contours of feature points obtained from a range of different spatial frequency tuned channels. We illustrate its performance on a series of natural images.

Matching method and device for automatic cutting of patterned fabrics

Abstract: Method and device for completing the automatical matching of panels to be cut in patterned fabrics to ensure that the de­sign for each one of the panels to be cut is in its correct position. After defining a series of matching points on each of the patterns and recording as digital data in a memory the matching relationships for each one of these points are de­fined and stored as matching information in the memory, the matching itself is carried out using a TV-camera (12) installed on the cutting machine (11), capturing images from any point of the fabrics being spread in connection with a digital image processing unit which, by processing the images captured, fix the real position of the design on the fabrics. Matching device, integrated marking and a cutting system are connec­ted in such a way to process the image information with the predicted matching relations to generate an adjustment to the position initially assigned to each panel - in both directions and in orientation - and guarantee a perfect cut of the panels.

Using Computers to Combat Welfare Fraud: The Operation and Effectiveness of Wage Matching

Abstract: In this study, David Greenberg and Douglas Wolf describe, systematize, and evaluate the cost effectiveness of computerized anti-fraud procedures in public welfare programs. In particular, they discusss the Congressionally mandated wage matching systems used to check for under-reported or non-reported incomes of participants in the AFDC and Food Stamp Programs. The authors describe the implementation of such systems in several local areas around the country, point out factors that currently impede the use of wage matching, and suggest ways of reducing such impediments. They also enumerate the advantages and disadvantages of alternative wage matching procedures and techniques, both in theory and practice. Cost benefit analyses of four existing wage matching systems are then presented. Finally, the authors present their conclusions and make recommendations. This volume is complete with a flow chart showing the operation of a typical wage-matching system, and a table summarizing the costs and benefits to the government of running such systems.