Showing papers on "Matching (statistics) published in 1982"

The Economics of Matching: Stability and Incentives

Abstract: This paper considers some game-theoretic aspects of matching problems and procedures, of the sort which involve matching the members of one group of agents with one or more members of a second, disjoint group of agents, ail of whom have preferences over the possible resulting matches. The main focus of this paper is on determining the extent to which matching procedures can be designed which give agents the incentive to honestly reveal their preferences, and which produce stable matches. Two principal results are demonstrated. The first is that no matching procedure exists which always yields a stable outcome and gives players the incentive to reveal their true preferences, even though procedures exist which accomplish either of these goals separately. The second result is that matching procedures do exist, however, which always yield a stable outcome and which always give all the agents in one of the two disjoint sets of agents the incentive to reveal their true preferences.

Resistant fits for some commonly used logistic models with medical application.

Abstract: Logistic regression-type models are used in many applications. Some examples include the classical dose-response experiment, prospective and retrospective studies of disease incidence (with and without matching), and the analysis of ordinal data. In most instances, the model is fitted by the method of maximum likelihood, which, like least squares, is sensitive to atypical observations. An alternative to maximum likelihood is proposed and illustrated by examples.

Cursive script recognition by elastic matching

Abstract: Dynamic programming has been found useful for performing nonlinear time warping for matching patterns in automatic speech recognition. Here, this technique is applied to the problem of recognizing cursive script. The parameters used in the matching are derived from time sequences of x-y coordinate data of words handwritten on an electronic tablet. Chosen for their properties of invariance with respect to size and translation of the writing, these parameters are found particularly suitable for the elastic matching technique. A salient feature of the recognition system is the establishment, in a training procedure, of prototypes by each writer using the system. In this manner, the system is tailored to the user. Processing is performed on a word-by-word basis after the writing is separated into words. Using prototypes for each letter, the matching procedure allows any letter to follow any letter and finds the letter sequence which best fits the unknown word. A major advantage of this procedure is that it combines letter segmentation and recognition in one operation by, in essence, evaluating recognition at all possible segmentations, thus avoiding the usual segmentation-then-recognition philosophy. Results on cursive writing are presented where the alphabet is restricted to the lower-case letters. Letter recognition accuracy is over 95 percent for each of three writers.

Fuzzy pattern matching

Abstract: Pattern‐directed inference systems (P.D.I.S.) are among the most largely used tools in A.I. to‐day in order to represent and exploit knowledge. Generally, P.D.I.S.'s use production rules triggered by matching between rule patterns and elements of the data base. However, the lack of flexibility in the matching remains a drawback in this kind of system. In the framework of the communication in natural language with robots, approximate descriptions of real world situations and approximately specified rules are needed; furthermore, similarity in the matching process does not always need to be perfect. Thus, the pervading fuzziness of natural language can be taken into account. The following levels, belonging to the real interval [0,1], are evaluated: The possibility of similarity between referents designated in the data and in the pattern respectively; the necessity that a referent designated in the data is similar to a referent designated in the pattern. Designations are fuzzy when the pattern or the data are fuzzy, which is usual with words of a natural language.

Matching, maximizing, and the hyperbolic reinforcement feedback function.

Abstract: A theory of hyperbolic feedback functions for schedules of reinforcement is developed, followed by an analysis of matching and maximizing behavior in an environment characterized by such feedback functions. The hyperbolic function classifies schedules along two dimensions: one that measures the time and one • that measures the responses that are needed to collect a unit of reinforcement. Among other results it is shown that (a) both response rules predict pairwise linearity, a condition which states that absolute rates of response on any two schedules are mutually constrained by a linear function, (b) matching and maximizing rules predict identical behavior if and only if the predictions of either one are consistent with Luce's choice axiom, and (c) the hyperbolic feedback function is preserved under aggregation of response classes. The evidence collected from single and concurrent schedules of reinforcement strongly favors the matching interpretation of equilibrium behavior, as subjects do not seem to be influenced by the marginal trade-offs that define the maximizing behavior distribution. It is argued that insensitivity to marginal variables undermines not only the specific hypothesis of reinforcement-rate maximization but also the more general theories of value maximization developed by Rachlin, Staddon, . and others.

The effect of thematic content on cognitive strategies in the four-card selection task

Abstract: Prior studies have indicated that thematic materials facilitate reasoning on the four-card selection problem, a task that assesses ability to evaluate logical conditionals of the “if-then” form. Recently, however, attempts to replicate the thematic effect have failed. The present study investigated four content materials to determine which facilitated reasoning. Introductory psychology students were required to determine which card(s) needed to be “unmasked” in order to determine the truth or falsity of conditional rules. Thematic materials did not facilitate reasoning compared with abstract materials. Evidence for both matching and verification bias was obtained, but neither was sufficient to account for all selection patterns. Subjects may thus be using “cognitive short-circuiting” strategies, of which matching bias and verification bias are but two examples.

Covariance adjustment of relative-risk estimates in matched studies

Abstract: The matched-sample case-control study is widely used by epidemiologists to estimate the relative incidence of disease among persons exposed to different levels of one or more risk factors. An apparent limitation of such designs has been the necessity to control the effects of all potential confounding variables in the matching process. Conditional likelihood analyses based on the linear logistic equation enable one to model the effects of covariates while preserving the original matching. This paper reviews the logical basis for this methodology and illustrates its value by application to a case-control study of esophageal cancer.

Classification of handprinted Kanji characters by structured segment matching method

Abstract: A method for handprinted Kanji character classificatin is proposed in this paper. After extraction of directional line segments and partitioning of the character frame area, a feature vector that represents the distribution of strokes is generated and is matched with average vectors in a dictionary.

Cost and efficiency in the choice of matched and unmatched case-control study designs

Abstract: This study compares matched and unmatched case-control designs in terms of the precision with which one can estimate an exposure-disease association while controlling for the effects of a confounding variable. Provision is made for the cost of the matching process by calculating the reduction in the number of controls that can be studied for fixed study cost. The purpose is to provide epidemiologists with guidelines and quantitative procedures for making rational decisions as to which is the more appropriate study design for specific research problems. The results indicate that when the cost of the matching process is negligible, a matched design is usually more efficient than an unmatched one. The difference in efficiency is generally slight, however, and is found to depend primarily on the strength of the confounder-disease association, the prevalence of exposure, and the strength of the exposure-disease association. When the cost of the matching process is not negligible, a matched design is likely to be less efficient than an unmatched one.

Effects of Self-Recording and Self-Recording + Matching on Academic Performance

Abstract: The purpose of the present research was to determine if self-recording and self-recording + matching could increase academic performance in programmed reading of six special education students. The results indicate that self-recording or baseline (no programmed consequence) across the six pupils. Follow-up data taken 20,30, 50, and 70 days after the study was terminated reveal that academic performance continued to improve even though no consequences were in effect. Accuracy of self-recording was higher during the self-recording + matching conditions for each of the six students. Practical aspects of the procedures were listed. The superior maintenance of treatment effects produced by the self-recording + matching condition was discussed.

In defense of matching

Abstract: This paper discusses the simplified situation of an epidemiologic study involving disease, exposure, and a single (possibly confounding) extraneous factor, all of which are dichotomous. The question is: In studying the association between disease and exposure, should the comparison group be selected by random sampling or by matching on the extraneous factor? An example is used to demonstrate the general principle that matching controls confounding in estimating the risk ratio in a follow-up study, but not in estimating the exposure odds ratio in a case-control study. Calculations based on a probability model show that, despite the possible reduction in sample size which may be associated with matching, matching will often lead to a more precise estimate of the effect measure than random sampling and is not likely to result in a significant loss in precision in situations of practical importance. Therefore, selection of the referent group by matching should be given serious consideration for both follow-up and case-control studies.

On the analysis of studies of choice.

Abstract: In a review of 103 sets of data from 23 different studies of choice, Baum (1979) concluded that whereas undermatching was most commonly observed for responses, the time measure generally conformed to the matching relation. A reexamination of the evidence presented by Baum concludes that undermatching is the most commonly observed finding for both measures. Use of the coefficient of determination by both Baum (1979) and de Villiers (1977) for assessing when matching occurs is criticized on statistical grounds. An alternative to the loss-in-predictability criterion used by Baum (1979) is proposed. This alternative statistic has a simple operational meaning and is related to the usual F-ratio test. It can therefore be used as a formal test of the hypothesis that matching occurs. Baum (1979) also suggests that slope values of between .90 and 1.11 can be considered good approximations to matching. It is argued that the establishment of a fixed interval as a criterion for determining when matching occurs, is inappropriate. A confidence interval based on the data from any given experiment is suggested as a more useful method of assessment.

Remarks on system simplification under consideration of time responses

Abstract: The letter highlights the significance of matching the terms of expansions around several points including s=0 and s=∞ in realising improved overall time-response approximation.

Speech recognition with preliminary matching

Abstract: Speech recognition executes the final matching operation for each characteristic pattern according to the preliminarily selected order prior to the final matching, where any further calculation in reference to such a characteristic pattern is not executed after a specific condition has been satisfied during the matching calculation, and as result, calculation requirements can be drastically minimized so that the speech recognition can eventually be implemented at higher speed and yet under a sharply reduced cost.

Nonperiodic sampling and model matching

Abstract: It is shown that the compensator matrices in matching problems may be obtained from a system of equations using arbitrary sampling on the impulse-response matrices of both the given system and its reference model. The sampling is used to achieve an acceptable transmission of the measuring errors.

From abstract model to efficient compilation of patterns

Abstract: Pattern matching is a technique which is used in many application areas such as text manipulation in editors, manipulation of arithmetic formulas in computer algebra systems and in artificial intelligence applications. In programming systems it can be a built-in language facility as string matching in SNOBOL4 or a language extension for matching of list structures as in INTERLISP.