The first thing that struck me when I donned my Fitbit Zip was that you wear this little beauty throughout the day and there's no way to turn it on and off. The reason this was of interest to me is that my ride home involves a bumpy road that seems to breed potholes, so I wondered if driving in my truck would trick my Fitbit into thinking I was walking or running.
All I can say is that there is some serious DSP (digital signal processing) taking place. I checked the step count before I set off and again when I arrived home. After travelling more than 10 miles over a very boisterous route in the "bumps department," my Fitbit Zip had only incremented its count by two steps. Personally, I think this is little short of miraculous.
The next morning when I came into work, I decided to try a few things. My typical garb in the summer is shorts, sandals, and a Hawaiian shirt. My leather sandals tend to flap around a bit, much like flip flops. Keeping this picture in mind, I noted the current step count and then started to walk around my office building with the Fitbit clipped to my shirt's breast pocket. I counted 100 steps and then stopped and checked the count against my Fitbit. Sad to relate, there was a noticeable error.
I then repeated the experiment with the Fitbit attached to different parts of my body (well, to different parts of my clothing) as illustrated below:
I might note that all this took a lot longer than you might expect. I didn't have a piece of paper or a pen with me, so I was doing it all in my head (which is why I don't recall the exact values). Also, I'm easily distracted, so I'd see something interesting and lose my count, or I'd stop at 100 steps and realize I couldn't recall the starting value. I'm sure the other folks in the building (a) got tired of seeing me walking past their windows and (b) wondered what the heck I was doing.
The bottom line is that in each case (Fitbit clipped to shirt pocket, short center, pants side picket, and pants center), there was some amount of error in the step count. I found this to be a little disquieting. I'm a bit of an obsessive compulsive when it comes to things like this. You can call me old-fashioned if you will, but I do like my numbers to add up to the correct value.
Of course, most folks don't perform serious training in flip flops, so my next step (no pun intended) was to exchange my sandals for socks and sneakers and to repeat the experiment. In this case, I'm delighted to say that my Fitbit Zip was pretty much 100 percent accurate irrespective of the location to which it was attached -- I don't think it ever miscounted by more than one step per test.
Now, this is where things get interesting, because I then repeated the entire suite of tests while walking on the desk treadmill in my office. What do you suppose I saw?
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