Abstract: A method for preparing a trained complete selective classifier can be applied to a trained complete selective classifier having an existing trained selection mechanism. The trained selective classifier is modified to disregard the existing trained selection mechanism and use, as a basis for an alternate selection mechanism, at least one classification prediction value, for example the predictive entropy or the maximum predictive class logit. Optionally, before modifying the trained selective classifier, the method commences with an untrained selective classifier, which may be trained with a modified loss function to obtain the trained selective classifier. The modified loss function has at least one added term, relative to an original loss function, and the at least one added term decreases entropy.

Abstract: The user gesture data collection system (100), comprises: - a portable (105) fragrance delivery device, - a relative positioning tracker (110) configured to detect the positioning of the portable fragrance device relative a facial feature of a user and - a data storing means (115) storing data based on the relative positioning detected.