7,582 research outputs found

    Criterion-referenced measurement: Its main applications, problems and findings

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    The need for criterion-referenced measurements has mainly arisen from the introduction of instructional programs organized according to modern principles from educational technology. Some of these programs are discussed, and it is indicated for what purposes criterion-referenced measurements are used. Three main problems of criterion-referenced measurement are distinguished: The problem of criterion-referenced scoring and score interpretation, the problem of criterion-referenced item and test analysis, and the problem of mastery testing. For each of these problems a variety of solutions of the paper to provide an overview of these and to introduce the reader to the original literature

    Passing score and length of a mastery test

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    A classical problem in mastery testing is the choice of passing score and test length so that the mastery decisions are optimal. Thsi problem has been addressed several times from a variety of view-points. In this paper the usual indifference zone approach is adopted with a new criterion for optimizing the passing score. It appears that, under the assumption of the binomial error model, this yields a linear relationship between optimal passing score and test length, which subsequently can be used in a simple procedure for optimizing the test length. It is indicated how different losses for both decision errors and a known base rate can be incorporated in the procedure, and how a correction for guessing can be applied. Finally, the results in this paper are related to results obtained in sequential testing and in the latent class approach to mastery testing

    A generalized approach for the calculation and automation of potentiometric titrations Part 1. Acid-Base Titrations

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    Fast and accurate calculation procedures for pH and redox potentials are required for optimum control of automatic titrations. The procedure suggested is based on a three-dimensional titration curve V = f(pH, redox potential). All possible interactions between species in the solution, e.g., changes in activity coefficients and influences of redox potential on pH variations, are taken into account. The number of titrant additions can be reduced considerably without loss of precision, by using the fact that the pH of a protolyte or mixture of protolytes at some fraction titrated does not depend strongly on the actual concentration

    Molecular Gastronomy: A Food Fad or an Interface for Science-based Cooking?

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    A review is given over the field of molecular gastronomy and its relation to science and cooking. We begin with a brief history of the field of molecular gastronomy, the definition of the term itself, and the current controversy surrounding this term. We then highlight the distinction between molecular gastronomy and science-based cooking, and we discuss both the similarities and the distinctions between science and cooking. In particular, we highlight the fact that the kitchen serves as an ideal place to foster interactions between scientists and chefs that lead to benefits for the general public in the form of novel and high-quality foods. On the one hand, it can facilitate the implementation of new ideas and recipes in restaurants. On the other hand, it challenges scientists to apply their fundamental scientific understanding to the complexities of cooking, and it challenges them to expand the scientific understanding of many chemical and physical mechanisms beyond the common mass-produced food products. In addition, molecular gastronomy forms an ideal base to educate the general public about the basic principles of science and cooking and how they can be utilized to improve the awareness of the role of food and nutrition for the quality of life

    A generalized approach for the calculation and automation of potentiometric titrations Part 2. Redox Titrations

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    The very fast calculation procedure described earlier is applied to calculate the titration curves of complicated redox systems. The theory is extended slightly to cover inhomogeneous redox systems. Titrations of iodine or 2,6-dichloroindophenol with ascorbic acid are described. It is shown that correspondence between theory and practice is good as long as the relevant stability constants and redox potentials are known with sufficient accuracy

    Delivery of Functionality in Complex Food Systems: Physically Inspired Approaches from Nanoscale to Microscale, Wageningen 18-21 October 2009

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    The Wageningen Delivery of Functionality symposium covered all aspects involved with food structural design to arrive at high-quality foods which meet demanding customer expectations and regulatory requirements. The symposium integrated aspects from the structural organization of foods at molecular and supramolecular scales to dedicated techniques required to describe and visualize such structures, the gastro-intestinal events and how to model these in a laboratory setting, and finally the impact those food structures and ingredients have on the consumer’s physiology and on the human perception. As an interdisciplinary platform, bringing together more than 160 researchers from academia and industry, the symposium meanwhile fulfills an important role in the food science communit

    Some procedures for computerized ability testing

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    For computerized test systems to be operational, the use of item response theory is a prerequisite. As opposed to classical test theory, in item response models the abilities of the examinees and the properties of the items are parameterized separately. Hence, when measuring the abilities of examinees, the model implicitly corrects for the item properties, and measurement on an item-independent scale is possible. In addition, item response theory offers the use of test and item information as local reliability indices defined on the ability scale. In this chapter, it is shown how the main features of item response theory have given rise to the development of promising procedures for computerized testing. Among the topics discussed are procedures for item bank calibration, automated test construction, adaptive test administration, generating norm distributions, and diagnosing test scores

    Measuring thermal conductivity in extreme conditions: sub-Kelvin temperatures and high (27 T) magnetic fields

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    We present a one-heater-two-thermometer set-up for measuring thermal conductivity and electric resistivity of a bulk sample at low temperatures down to 0.1 K and in magnetic fields up to 27 Tesla. The design overcomes the difficulties emerging in the context of large water-cooled resistive magnets.Comment: 4 pages including 4 figure

    Decision models for use with criterion-referenced tests

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    The problem of mastery decisions and optimizing cutoff scores on criterion-referenced tests is considered. This problem can be formalized as an (empirical) Bayes problem with decisions rules of a monotone shape. Next, the derivation of optimal cutoff scores for threshold, linear, and normal ogive loss functions is addressed, alternately using such psychometric models as the classical model, the beta-binomial, and the bivariate normal model. One important distinction made is between decisions with an internal and an external criterion. A natural solution to the problem of reliability and validity analysis of mastery decisions is to analyze with a standardization of the Bayes risk (coefficient delta). It is indicated how this analysis proceeds and how, in a number of cases, it leads to coefficients already known from classical test theory. Finally, some new lines of research are suggested along with other aspects of criterion-referenced testing that can be approached from a decision-theoretic point of view