dfset function

Find degrees of freedom for a natural spline curve to minimise BIC or AIC

dfset fits a natural cubic spline for a range of degrees of freedom, and returns the df minimising the BIC or AIC.

dfset(x, y, data = parent.frame(), FUN = BIC, df = 1:15, plot = FALSE, ...)

Arguments

• x: vector of x coordinates.
• y: vector of y coordinates.
• data: environment containing x and y.
• FUN: function to be minimised (e.g. BIC or AIC).
• df: vector of degrees of freedom to be searched.
• plot: logical controlling plotting of FUN versus df.
• ...: parameters to pass to plot.

Returns

degrees of freedom and value of FUN at minimum.

Examples

data(heights)
dfset(age, height, heights, FUN=BIC, plot=TRUE)
dfset(age, height, heights, FUN=function(a) AIC(a, k=1))

Author(s)

Tim Cole tim.cole@ucl.ac.uk