Analysis of embryonic development with a model for under- or overdispersion relative to binomial variation.
Observations from a study of the development of ovulations into embryos for Texel sheep are analysed with a model for count data that are under- or overdispersed relative to binomial variation. The analysis is based on maximum quasi-likelihood (McCullagh and Nelder, 1989, Generalized Linear Models, 2nd edition, London: Chapman and Hall), following an approach suggested by Williams (1982, Applied Statistics 31, 144-148). The dispersion parameter is developed as a combination of a variance component representing shared maternal effects and a correlation, typically negative, between ovulations within ewes. The number of ovulations (the binomial denominator) is included as an explanatory variable.
Engel
B
B
Agricultural Mathematics Group, Wageningen, The Netherlands.
te Brake
J
J
D000735:Androstenedione / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D016010:Binomial Distribution; D001699:Biometry; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005260:Female; D005298:Fertility / Q000187:drug effects; D016013:Likelihood Functions; D008954:Models, Biological; D015233:Models, Statistical; D010060:Ovulation / Q000187:drug effects; D011247:Pregnancy; D012709:Serum Albumin / Q000494:pharmacology; D012756:Sheep
D012709:Serum Albumin; C042013:polyandroalbumin; D000735:Androstenedione