A complete system is described for electronically processing and analyzing metabolic data which are used to estimate radiation protection guides for man. Counting data from multichannel liquid scintillation detectors, together with experimental information which is manually dialed into the punch control unit of the counter, are automatically punched onto paper tape or IBM data cards. The cards comprise the input for a computer program (RTW) which will calculate elapsed time between radionuclide administration and time of measurement, correct all data for changes in counting efficiency relative to measurements made on standards at zero time and for physical decay, if desired, and express the observed counting information as effective or biological retention at any time after the initial measurement. Portions of the RTW program output are on IBM data cards in a format compatible with the input requirements for a least squares computing method programmed for the IBM 7090 which, in turn, will derive the parameters of the function which “best fit” the data. Lastly, a General-Dynamics Model SC-4020 tape-to-film device is used to produce on 35-mm film a plot of the observed retention data, the fitted curve, and ancillary labeling statements.