Showing papers on "Matching (statistics) published in 1991"

Matching People and Organizations: Selection and Socialization in Public Accounting Firms

Abstract: Understanding and predicting behavior in organizations requires a consideration of person and situation factors, and how these factors interact. This paper develops and longitudinally tests a model...

Matching properties of MOS transistors

Abstract: The matching properties of the threshold voltage, substrate factor and current factor of MOS transistors have been analysed and measured. Improvements of the existing theory are given, as well as extensions for long distance matching and rotation of devices. The matching results have been verified by measurements and calculations on a band-gap reference circuit.

Discussing hidden bias in observational studies.

Abstract: In observational studies or nonrandomized experiments, treated and control groups may differ in their outcomes even if the treatment has no effect; this may happen if the groups were not comparable before the start of treatment. The groups may fail to be comparable in either of two ways: They may differ with respect to characteristics that have been measured, in which case there is an overt bias, or they may differ in ways that have not been measured, in which case there is a hidden bias. Overt biases are controlled through adjustments, such as matching. Hidden bias is more difficult to address because the relevant measurements are not available. A sensitivity analysis asks how much hidden bias would need to be present if hidden bias were to explain the differing outcomes in the treated and control groups. A sensitivity analysis provides a tangible and specific framework for discussing hidden biases.

Automatic impedance matching apparatus and method

Abstract: An automatic impedance matching apparatus for matching an RF-signal generator to a load, such as a plasma etching chamber, is disclosed. The matching apparatus comprises a matching network having two variable impedance devices, a tune detector for detecting the condition of the impedance match between the RF-signal and the load, and a controller for modifying the values of the variable impedance components in response to the measured tune condition. The present invention disclosed improve reset and convergence unit and eliminates the need for the "dead-band" provided around the matching point found in prior art impedance matching controllers. Also disclosed is an improved adjustment unit for adjusting the variable impedance components which is faster and more stable than found in prior art controllers. Also disclosed is a normalization unit for normalizing the input detection siganls such that variations in turning performance due to variations in input power level from the source are substantially reduced.

Randomized Recruitment in Case-Control Studies

Abstract: A new sampling approach for case-control studies offers a flexible alternative to frequency matching. In the "randomized recruitment" method, subjects are individually randomized to be recruited or not on the basis of investigator-imposed recruitment probabilities that can depend on both disease status and values of covariates already available or ascertained in a screening interview. When there is prior information about the odds ratios associated with the screening variables, such a design can achieve "probability matching," without the well-known disadvantages that encumber traditional matching. The method can also be used to enlarge the relative size of subsamples of interest. Following randomized recruitment, a modified logistic regression analysis allows unbiased estimation of effects associated with all variables studied, including the "matching" variables. One can also readily fit an additive model. The method is illustrated by developing the recruitment probabilities required for probability matching on age, sex, and cigarette smoking status in an ongoing study of lung cancer and exposure to radon progeny in which smoking cases are undersampled.

Sorority Rush as a Two-Sided Matching Mechanism

Abstract: The history and organization of the membership recruitment process of American sororities is studied Like entry-level labor markets studied previously, this process experienced failures that led to the adaptation of a centralized matching procedure in which a matching is determined on the basis of preference lists submitted by the agents Analysis of the rules of the match and of preference lists from twenty-one matches reveals an unstable matching procedure that gives agents incentives to behave strategically The analysis also shows how the agents act on these incentives and how the resulting strategic behavior has contributed to the longevity of the matching system and to the stability of the resulting matches Copyright 1991 by American Economic Association

Record linkage strategies. Part I: Estimating information and evaluating approaches.

Abstract: Record linkage techniques can help identify the same patient for matching diverse files (hospital discharge abstracts, insurance claims, registries, Vital Statistics data) which contain similar identifiers. Prior knowledge of whether a linkage is feasible is important to prevent wasted effort (additional data collection or data manipulation), which decreases the cost-effectiveness of the linkage. Using examples generated by linking the Manitoba Health Services Commission data with Vital Statistics files, a method of estimating the information in each data set is presented first. Further, the feasibility of several different record linkage strategies is described and tested, given varying amounts of information. At the margin, relatively small amounts of information (having just one more variable to match with) can make a great difference. Probabilistic linkage’s great advantage was found in those situations where only a moderate amount of extra information was available. By using the above techniques when working with one or both files in a proposed record linkage project, a much more informed judgement can now be made as to whether a linkage will or will not work. In facilitating record linkage, flexibility of both software and the strategy for matching is very important.

Three-dimensional stable matching problems

Abstract: The stable marriage problem is a matching problem that pairs members of two sets. The objective is to achieve a matching that satisfies all participants based on their preferences. The stable roommate problem is a variant involving only one set, which is partitioned into pairs with a similar objective. There exist asymptotically optimal algorithms that solve both problems.In this paper, the complexity of three-dimensional extensions of these problems is investigated. This is one of twelve research directions suggested by Knuth in his book on the stable marriage problem. It is shown that these problems are NP-complete, and hence it is unlikely that there exist efficient algorithms for their solutions.The approach developed in this paper provides an alternate NP-completeness proof for the hospitals/residents problem with couples—an important practical problem shown earlier to be NP-complete by Ronn.

Electronic learning machine which is capable of giving learning problems matching the student's scholastic ability

Abstract: An electronic learning machine having an input unit for inputting data relating to a specific student. When the data relating to the student is entered by the input unit, a select unit selects the scholastic achievement data related to the student from a first storage unit. A control unit then selects, when so directed, problem information matching the student's scholastic ability from problem information at all difficulty levels stored in a second storage unit and displays the selected problems on the display or on a printing paper. Thus, the student is faced with problems at a difficulty level matching his/her scholastic ability to enhance learning.

A methodology for choosing data representations

Abstract: The process of matching the type of information of interest with the ability of the different representation properties to convey this information is formalized in a generic framework. Visualization approaches are discussed, and the natural scene paradigm on which the methodology for choosing a representation is based is described. Data types and interpretation aims are explored. The use of the paradigm, the matching process, and implementation and display of the representation are described. The advantages of the methodology over ad hoc display approaches are examined. >

Matching Of Medical Images For Computed And Robot Assisted Surgery

Abstract: This paper adresses the application of matching techniques to Computer and Robot Assisted Surgery, where we desire to use in the surgical theater a treatment planning based on multi-modal data (mainly pre-operative images). We present a methodology based on geometrical matching of reference anatomical surfaces. Then we describe a new general method that enables to perform 3-D / 2-D matching and 3-D / 3-D matching with fast computation. Results are illustrated.

The efficiency of the Dutch labour market in matching unemployment and vacancies

Abstract: A matching function specifies the relationship between the flow of filled job vacancies and the stocks of unemployed and job vacancies. This paper specifies and estimates the matching function of the Dutch labour market. It appears that this matching function is best described by a Cobb-Douglas function with constant returns to scale and coefficients of 0.4 on unemployment and 0.6 on vacancies. The matching function shifted at the end of the sixties and remained quite stable afterwards. This indicates that with a higher level of unemployment and lower level of job vacancies the Dutch labour market today is as efficient in generating a flow of filled vacancies as it was in the seventies.

Minimax Grid Matching and Empirical Measures

Abstract: In this article we solve the minimax grid matching problem in dimensions greater than two. As a by-product, we settle a long-open problem involving the Glivenko-Cantelli convergence of empirical measures.

Results of test on image matching of ISPRS WG III/4

Abstract: In 1986 an empirical test on image matching was initiated by ISPRS WG III/4. The main purpose of the test was to find out the state of the art of image matching procedures applied in the fields of computer vision, pattern recognition and photogrammetry. The paper presents the summarized results of the test analysis. A comparative study of approaches and strategies is performed using different criteria for their classification. To study the precision and reliability of the procedures, the matching results are compared with manual or computational checks. Attention is also focused on the possibilities of the procedures for quality assessment or selfdiagnosis.

Temporally distributed symptoms in technical diagnosis

Abstract: Related work.- Temporal matching.- Incorporating TDSs into existing diagnostic paradigms.- Conclusion.

Matching Processes in the Labor Market

Abstract: Quantitative research in occupational mobility has typically focused on individual status attainment, examining the effect of background and individual characteristics on the attainment of status (or, infrequently, on mcomes). Yet the labor market involves a matching process in which the matches between persons and jobs are determined by the resources of the person, relative to those of other persons in the market, the resources of the job, relative to those of other jobs, the interest of the employer in the person's resources, and the mterest of the person in the job's resources A model is presented, assuming a perfect market of resource exchange, in which the value of the resources a person brings to the job is equal to the value of the job's resources. The model allows estimation of the value of each resource in the labor market. It is applied to data on a representative sample of the US labor force, allowing estimation of the value of various resources of persons and jobs in the US labor market in 1986.

On the Social Science Contribution to Governmental Decision-Making

Abstract: It is often said that a major impediment to effective government is the lack of research knowledge underlying the development, implementation, and assessment of federal policies and programs. An examination is made here of the causes of (i) some continuing failures in integrating research information with decision-making and (ii) some notable successes of the past two decades in matching research capabilities with policy needs. Six recommendations are made to facilitate and further the progress that has recently been achieved.

Matching factors for various light-source-photodetector combinations

Abstract: The matching between the spectral distribution of the light emitted from a light source and the spectral distribution of the sensitivity of a light detector is characterized by the “matching factor”. In the paper we present a table of 500 matching factors for the combination of various phosphors with the most common photodetectors.

Personal verification system with high tolerance of poor-quality fingerprints

Abstract: A highly reliable personal verification system using fingerprint images has been developed. Various image enhancement techniques including a directional spatial filter and local thresholding for each point are applied to improve the quality of noisy and unstable images and to extract the feature data as accurately as possible. This process is performed by our special hardware for rapid image processing operations. In the matching process we propose a new algorithm combining the coarse matching of ridge direction data with the precise matching of minutia data to achieve registration efficiently. This system provides high reliability and a real-time response at reasonable cost.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fingerprint matching device

Abstract: PURPOSE:To obtain a fingerprint matching device in which matching time can be shortened for a fingerprint inputted frequently. CONSTITUTION:A matching number setting means 7 counts the number of times of matching at every case when coincidence is obtained by matching the fingerprint with fingerprint registration data in memory 4 for fingerprint registration, and a priority setting means 8 finds the priority of every piece of fingerprint registration data, respectively based on the number of times of matching, and a registration fingerprint data area change means 9 performs the change of registration on a new area in registration areas in the memory for fingerprint registration in sequence of the fingerprint registration data with highest priority, thereby, it is possible to shorten the matching time for the fingerprint inputted most frequently.

Flexible matching for noisy structural descriptions

Abstract: Uncertainty on data often makes the task of perfectly matching two descriptions quite ineffective. In this case, a flexible matching, measuring the similarity of two descriptions rather than their equality, is more useful. According to the convention of connecting similarity to the most common concept of distance, we present a definition of distance measure, based on a probabilistic interpretation of the matching predicate, which can cope with structural deformations. As the problem of matching two formulas of the FOPL is NP-complete, two methods arc presented in order to cope with complexity: firstly, a branch-and-bound algorithm, and secondly, a heuristic method. These ideas are applied to the problem of recognizing office documents in digital form according to their page layout.