Cellular Differentiation
The effect of two agents of immuno-activating ability that may induce cell differentiation was investigated.
data(cells)
A data frame with 16 observations on the following 3 variables.
number of cells differentiating
dose of TNF, U/ml
dose of IFN, U/ml
The effect of two agents of immuno-activating ability that may induce cell differentiation was investigated. As response variable the number of cells that exhibited markers after exposure was recorded. It is of interest if the agents TNF (tumor necrosis factor) and IFN (interferon) stimulate cell differentiation independently, or if there is a synergetic effect. 200 cells were examined at each dose combination.
Kjetil Halvorsen
Ludwig Fahrmeir, Gerhard Tutz (1994): Multivariate Statistical Modelling Based on Generalized Linear Models. Springer Series in Statistics. Springer Verlag. New-York Berlin Heidelberg
str(cells)
cells.poisson <- glm(y~TNF+IFN+TNF:IFN, data=cells,
family=poisson)
summary(cells.poisson)
confint(cells.poisson)
# Now we follow the book, example 2.6, page 51:
# there seems to be overdispersion?
cells.quasi <- glm(y~TNF+IFN+TNF:IFN, data=cells,
family=quasipoisson)
summary(cells.quasi)
anova(cells.quasi)
confint(cells.quasi)
# We follow the book, example 2.7, page 56:
with(cells, tapply(y, factor(TNF), function(x) c(mean(x), var(x))))
# which might indicate the use of a negative binomial modelPlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.