A computer-aided data-interpretation system is described that combines the abilities of a human operator for pattern recognition and decision making with those of a digital computer for rapid computation. It is designed for the specific task of converting ionograms to electron density N(h) profiles, but is sufficiently flexible in design and concept to be used, in principle, with any type of complex datum. The system consists of a small computer with an associated cathode-ray tube display, a human operator, and a large main computer. The small computer is used to digitize and store the ionogram tape and maintain the CRT display. The operator scales a trace representing one of the magnetoionic modes of the displayed ionogram, and commands the main computer to calculate the corresponding N(h) profile and the ionogram that would result from the computed profile. The operator then compares the remaining traces of the original and computed ionogram via the display, and either verifies the scaling or rescales the ionogram until the desired agreement has been achieved. The system permits the scaling, for N(h) analysis, of complex ionograms which otherwise could not be used for this purpose without great labor.