A method of determining the analyte concentration of a test sample is described. The dielectric housing includes a mating face, a pair of side walls extending from the mating face and a mating space in the mating face between the side walls. A nozzle is in communicative connection with the conduit such that the oxygen flow the conduit receives is conducted to the nozzle. The trained statistical model, the first statistical model, and the second statistical model, being independent of each other and collectively used to classify another sample.