1. the observed response of the sensor m (the input data to the inverse problem) is corrupted by measurement noise , hence likely δ = 0 2. the partial pressure of the interferent in the sensing environment exhibits variance, hence likely p 0 i = p0 i . Importantly, seen via eqn. 6 the magnitude of the error depends not only on δ and p 0 i -p0 i , but also on (1) design parameters of the CF-GS: the residence time of gas in the catalytic filter (r ), the catalyst (k i , k a ), the recognition element of the sensor (K i , K a , N), (2) the molecular weights of the interferent and analyte (w i , w a ), and (3) the partial pressure of the analyte in the unadulterated gas (p 0 a ). Intuitively, the catalytic filter, if it converts a large fraction of the interferent, makes assumption (2) less consequential on the error in the predicted partial pressure of the analyte.