with the predicted gas composition p0 a through solving the modified inverse problem, given in eqn. 6. A fit CF-GS will have small E[| P 0 a -P 0 a |]. Conceptually, the performance metric E[| P 0 a -P 0 a |] is based on a probabilistic model mimicking repeated deployment of a CF-GS in the sensing environment: (1) sample a gas composition (p 0 a , p 0 i ) from f P 0 a ,P 0 i , (2) observe the response of the sensor m, governed by eqn. 4, via sampling measurement noise δ from f ∆ , (3) use the observed response of the sensor to predict the partial pressure of the analyte, p0 a , from eqn. 6, then (4) compare this prediction to the true partial pressure p 0 a , i.e. compute the error p0 a -p 0 a . Eqn. 7 is the average error under this stochastic process.