A method of determining affinity for a molecular binding interaction from measured steady state binding data comprises the steps of: a) providing a plurality of experimental binding data sets for the binding interaction between two chemical species, wherein each data set includes binding data measured at multiple time points during an association phase and a dissociation phase of the interaction, b) selecting from the plurality of experimental binding data sets a plurality of binding data measured at a defined time point at or near the end of the association phase as representing steady state binding data, c) subjecting each data set to a quality control which comprises estimating the reliability of the steady state binding data by evaluating other binding data of the same data set, d) excluding each data set which is estimated in step c) to contain unreliable steady state binding data, and e) determining the affinity from the steady state binding data of remaining data sets.