Journal Article: Beta-binomial tables for replicated difference and preference tests (1999)

Abstract: Ennis and Bi (1998) discussed the beta-binomial (BB) model for replicated diflerence and preference tests. Based on the BB model, tables of the minimum number of choice responses to achieve significance at a ?0.05 are provided for replicated 2-AFC, Duo-Trio, 3-AFC and Triangular tests. The theory underlying the tables, how to use the...

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Journal Article: The power of sensory discrimination methods used in replicated difference and preference tests (1999)

Abstract: Research on the power of discrimination methods in difference and preference tests has both theoretical and practical significance. Power is important to evaluate the sensitivities of tests and determine sample size. Ennis and Bi (I 998, 1999) proposed the beta-binomial distribution to model replicated difference and preference tests with inter-trial variation and analyzed...

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Journal Article: Mustard discrimination by same-different and triangle tests: Aspects of irritation, memory and t criteria (1999)

Abstract: The utility of the same-different protocol when studying very fatiguing products (Dijon style mustard), as well as when inspecting consumers' abilities to discriminate among food products, was confirmed. The stabilizing effect of a familiarization procedure on the t criterion variations in the same-different test was investigated. Using an independent samples design, and the...

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Journal Article: The Dirichlet-multinomial model: Accounting for inter-trial variations in replicated ratings (1999)

Abstract: Differences in sensory acuity and hedonic reactions to products lead to latent groups in pooled ratings data. Manufacturing locations and time differences also are sources of rating heterogeneity. Intensity and hedonic ratings are ordered categorical data. Categorical responses follow a multinomial distribution and this distribution can be applied to pooled data over trials...

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Journal Article: A Thurstonian variant of the beta-binomial model for replicated difference tests (1998)

Abstract: The beta-binomial model is combined with a Thurstonian psychometric function to obtain estimates of the parameters of a distribution applicable to replicated difference tests. A method of estimating the variance of d' obtained from these tests is provided. A formula for determining sample size, which is composed of the number of trials (or...

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Journal Article: The beta-binomial model: Accounting for inter-trial variation in replicated difference and preference tests (1998)

Abstract: Binomial tests are commonly used in sensory difference and preference testing under the assumptions that choices are independent and choice probabilities do not vary from trial to trial. This paper addresses violations of the latter assumption (often referred to as overdispersion) and accounts for variation in inter-trial choice probabilities following the Beta distribution....

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Journal Article: Sensory thresholds: Concepts and methods (1998)

Abstract: A sensory threshold can be defined generally as a stimulus intensity that produces a response in half of the trials. The definition of the population threshold is discussed. Five main classical statistical procedures for estimating thresholds are reviewed. They are the probit, the logistic, the Spearman-Karber, the moving average and the up-and-down procedures....

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Journal Article: Foundations of sensory science and a vision for the future (1998)

Abstract: In his Nobel lecture on the development of the beta-antagonists and antihistamines, Black (1989) emphasized the importance of pharmacokinetic models in providing direction for his research. "Models...are not meant to be descriptions, pathetic descriptions of nature." he said. "They are designated to be accurate descriptions of our pathetic thinking about nature." Science is...

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Journal Articles: Thurstonian models for variants of the method of tetrads (1998)

Abstract: Variants of the method of tetrads are discussed and their psychometric functions are both derived and presented in table form. For the first variant, the Unspecified method, subject response is correct provided that the subject, when presented with two stimuli form one set and two stimuli from a second set, correctly segregates the...

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Journal Article: A new approach to category scales of intensity II: Use of d’ values (1998)

Abstract: Using a Rank-Rating method, d' values were obtained for stimuli from a model system using 15-point, 9-point, 7-point and 5-point category scales. For an apple/grape juice system, d' values were compared for 9-point and 7-point scales. There was general agreement on d' values among the scales, except where stimuli had their scores 'bunched'...

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