Last chance! 50% off unlimited learning
Sale ends in
Maximum likelihood estimation of the degrees of freedom for a chi-squared distribution. Also fits the chi distribution.
chisq(link = "loglink", zero = NULL, squared = TRUE)
An object of class "vglmff"
(see vglmff-class
).
The object is used by modelling functions
such as vglm
,
and vgam
.
See CommonVGAMffArguments
for
information.
Logical.
Set FALSE
for the chi distribution.
T. W. Yee
The degrees of freedom is treated as a real parameter to be estimated and not as an integer. Being positive, a log link is used by default. Fisher scoring is used.
If a random variable has a chi-squared distribution then the square root of the random variable has a chi distribution. For both distributions, the fitted value is the mean.
Forbes, C., Evans, M., Hastings, N. and Peacock, B. (2011). Statistical Distributions, Hoboken, NJ, USA: John Wiley and Sons, Fourth edition.
Chisquare
.
uninormal
.
cdata <- data.frame(x2 = runif(nn <- 1000))
cdata <- transform(cdata, y1 = rchisq(nn, df = exp(1 - 1 * x2)),
y2 = rchisq(nn, df = exp(2 - 2 * x2)))
fit <- vglm(cbind(y1, y2) ~ x2, chisq, data = cdata, trace = TRUE)
coef(fit, matrix = TRUE)
Run the code above in your browser using DataLab