While it is possible to analyze CRC data and determine IC 50 /EC 50 values in many ways, standard approaches that are considered best practices in the scientific community are codified in the Assay Guidance Manual (AGM). ? The AGM is a free online resource written by over 100 authors and managed by the National Center for Advancing Translational Sciences with input from experts working in industry, academia, and government. Its scope includes "appropriate statistical ways to analyze assay results and accommodate minor changes to assay protocols to ensure robustness. ? " According to the AGM, ? CRC data should first be normalized by control data. As described in the chapter "Data Standardization for Results Management", the specific type of control data depends on the type of assay. In enzymatic inhibition assays, negative controls contain the enzyme including cofactors and substrate(s), but no putative inhibitor. Positive controls also include substrate(s) and cofactors, but the enzyme is either absent or fully inhibited. Regardless of the assay, normalization is performed by subtracting the response by the minimum, dividing by the range (difference between minimum and maximum), and multiplying by 100 to obtain a percentage. For most assays, the minimum is the negative control and maximum the positive control. The exceptions are for in vitro functional assays of agonist and inverse agonists, in which the AGM recommends fitting to the CRC of a reference agonist to obtain the minimum and maximum.)