have xA, yA, and zA acceleration signals collected from a smartphone and I call it: set A and I also have xB, yB, and zB same acceleration signals from smartwatch: let's call this set B. I need to combine them together because I am trying to find which combination of devices give optimal result in regard to detect the subject's activities. I have more than these two sensors but I just ask about these two and then if I got an answer then apply it on all. I will combine smartphone with smartwatch, smartphone with sensor placed on upper arm and etc. However, I am not sure if this is right to do or doing this is eliminating necessary signals. Also, is this way better than only taking the average of these two sets. (A + B)/2 ?