The elements of a scanning probe microscope are modeled as a set of springs in series. For a single-component sample, that is, a sample consisting of only one material, the detected feature height in variable force (force microscopy) or variable current (tunneling microscopy) modes is a function of the total system stiffness and the stiffness of the detector. For a multicomponent sample, the data in both variable force (current) and constant force (current) modes are modified by the set-point force, the detector stiffness, and the relative stiffnesses of the components of the sample. A detection scheme for reducing this compliance effect is proposed.