### Abstract

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.

Original language | English |
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Pages (from-to) | 237-242 |

Number of pages | 6 |

Journal | Biometrics |

Volume | 49 |

Issue number | 1 |

DOIs | |

Publication status | Published - Mar 1993 |

Externally published | Yes |

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### Cite this

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*Biometrics*, vol. 49, no. 1, pp. 237-242. https://doi.org/10.2307/2532618

**A gamma model for extra-binomial variation in dilution assays.** / O'Neill, T J; O'Neill, H C.

Research output: Contribution to journal › Article › Research › peer-review

TY - JOUR

T1 - A gamma model for extra-binomial variation in dilution assays

AU - O'Neill, T J

AU - O'Neill, H C

PY - 1993/3

Y1 - 1993/3

N2 - 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.

AB - 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.

U2 - 10.2307/2532618

DO - 10.2307/2532618

M3 - Article

VL - 49

SP - 237

EP - 242

JO - Biometrics

JF - Biometrics

SN - 0006-341X

IS - 1

ER -