The present invention relates to the field of detection apparatus and/or methods. One aspect relates to an apparatus and/or detection methods for sensing material and/or detection of a predetermined characteristic within a detection zone. Another aspect relates to a method for improving the accuracy of an inspection device by capturing the human interpretation of its classification decision. Still another aspect relates to detection of relatively hard to detect items, for example items inside sealed packages. In a further aspect, the invention relates to a method of monitoring and/or improving the operation of a detection apparatus in which a detection result is obtained, and an adjustment (if necessary) is made in accordance with a comparison.