Spline Functions in Data Analysis

The use of spline functions in the analysis of empirical two-dimensional data (y i, x i) is described. The definition of spline functions as piecewise polynomials with continuity conditions give them unique properties as empirical function. They can represent any variation of y with x arbitrarily well over wide intervals of x. Furthermore, due to the local properties of the spline functions, they are excellent tools for differentiation and integration of empirical data. Hence, spline functions are excellent empirical functions which can be used with advantage instead of other empirical functions, such as poly-nomials or exponentials. Examples of application show spline analyses of response curves in pharmacokinetics and of the local behavior of almost first order kinetic data.