Full_Name: Benjamin Hofner Version: 2.9.1 OS: Ubuntu Submission from: (NULL) (92.229.82.215)
Hi I found some mistakes in the documentation of function bs() in package splines (I use R 2.9.1 but it also holds for the latest SVN Version https://svn.r-project.org/R/trunk/src/library/splines/man/bs.Rd) ----------------------------- \item{df}{degrees of freedom; one can specify \code{df} rather than \code{knots}; \code{bs()} then chooses \code{df-degree-1} knots at suitable quantiles of \code{x} (which will ignore missing values).} This should read (or similar): \item{df}{degrees of freedom; one can specify \code{df} rather than \code{knots}; \code{bs()} then chooses \code{df-degree-as.numeric(intercept)} knots at suitable quantiles of \code{x} (which will ignore missing values).} The problem here is: we only subtract 1 if we use an intercept! Probably this becomes more readable if one uses a construction as e.g. \code{df-degree-1} if \code{intercept=TRUE} and \code{df-degree} if \code{FALSE}. ----------------------------- The next problematic part is: A matrix of dimension \code{length(x) * df}, where either \code{df} was supplied or if \code{knots} were supplied, \code{df = length(knots) + 3 + intercept}. This should read (or similar): A matrix of dimension \code{length(x) * df}, where either \code{df} was supplied or if \code{knots} were supplied, \code{df = length(knots) + degree + as.numeric(intercept)}. Always adding 3 is not suitable. Furthermore the "+ intercept" is not very clear. Another issue is the dimension of the matrix: I would rather suggest to write it in LaTeX style "length(x) \times df". ----------------------------- I hope this helps to improve the docs a bit. Cheers, Benjamin ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
