Operational method for slope estimations

The operational method yields an abundance of new slope estimating formulae that apply to equidistant, curvilinear data. The performances of two of these new formulae are compared to the standard formula for center-point slope estimations on three data points. It is demonstrated that the standard formula is only a special case developed from the more general operational approach. New slope formulae at the terminal values of three curvilinear data are derived. Formulae applicable to more than three data points can also be obtained.