The influence of the parameterisation choice on the parameter landscape. A straight line is fitted through three datapoints. In subplot (a) the line is parameterized by intercept Ym(0) and slope s, giving Y = s*X + Ym(0). This parameterisation leads to the landscape shown under (b), which has a valley shape. In subplot (c) the line is parameterized by the two values Ym(1) and Ym(2), giving Y = (Ym(2)-Ym(1))*(X-1) + Ym(1). This parameterisation gives the trough-shaped parameter landscape shown under (d). Changing the parameterisation therefore drastically changes the landscape.