Fig. 5

A plot of age in years against the triceps skinfold thickness for 892 females in West Africa. Upper left: Dashed line represents a simple linear fit, solid line a fit using flexible third degree polynomials. Upper right: Splines fit using default R values. Green line is the result of a polynomial spline of degree 1 (default value for function poly, and a fit from a natural spline with no degrees of freedom specified (default value for functions ns). Red line comes from a b-spline with three degrees of freedom (function bs and blue line from a smoothing spline (from function smooth.spline). Lower left: Black line is polynomial fit, red line b-splines fit, green line is a natural splines fit and smoothing spline, all defined with four degrees of freedom. Lower Right: Same functions defined with 10 degrees of freedom. Created with Code #4