A gamma model for extra-binomial variation in dilution assays.
Dilution assays are widely used to estimate the concentration of a particular type of cell, called a limiting cell, in a population of cells from an animal. For each animal, the response vector is a set of binomial variables derived at different plating frequencies. Often extra-binomial variation is found when dilution assay data are analysed. This paper proposes a mixture model where the animal level effects are assumed to have a gamma distribution. This leads to more realistic standard errors for the estimates of the limiting cell concentrations.
Department of Statistics, Faculty of Economics and Commerce, Australian National University, Canberra ACT.
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O'Neill
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O'Neill
D000818:Animals; D001681:Biological Assay / Q000706:statistics & numerical data*; D001699:Biometry; D003114:Colony-Forming Units Assay / Q000706:statistics & numerical data; D016013:Likelihood Functions; D016015:Logistic Models; D051379:Mice; D015233:Models, Statistical