A system, transceiver, and method for calculating and correcting levels (e.g., analyte levels) in a first medium (e.g., blood) using measurements from a second medium (e.g., interstitial fluid). In some embodiments, a transceiver may calculate an initial second medium level. The transceiver may calculate an initial second medium level rate of change (“ROC”) using at least the initial second medium level and past second medium level(s). The transceiver may calculate a first medium level using at least the initial second medium level and the initial second medium level ROC. The transceiver may calculate a subsequent second medium level. The transceiver may calculate an updated second medium level ROC using at least the initial second medium level, the subsequent second medium level, and past second medium level(s). The transceiver may calculate a corrected first medium level using at least the initial second medium level and the updated second medium level ROC.