Well my husband thinks it is a joke. I just tell him use the same force each time. And I can tell if I am weaker or stronger. Do you have anyone at work that can test you? I am assuming you do not have anyone at home to do it. There is a girl I work with who is cool with helping me too. For some reason even if the other person doesnt really know what they are doing, I can still get my yes or no much more consistantly from them than when I do it myself. Katie