In a study I wrote in 2011 I analyzed the then available activity monitors for usabilty by non-self-quantifiers (aka “ordinary people”). At the time I concluded that the Fitbit (then there was only one model) was the most appropriate because it synchronized wirelessly and automatically and only need to be charged every 5-7 days. Since then several competitors have come out which are either wristband based (like the Jawbone Up which requires a cable to synchronize it) or clip-ons like the FitBit. FitBit have also expanded their range, with the lastest clip-on, the FitBit One, also measuring number of stairs climbed in addition to the activity and notional sleep of the original model. Like the original it also syncs wirelessly but this time by low power Bluetooth 4.0 rather than a proprietary charge/sync USB.
The other recent FitBit model is the less expensive FitBit Zip which also uses Bluetooth 4.0 and sports an even lower power LCD display activated by tapping it. This model uses a button sized dsiposable CR2032 battery which lasts about 3 months so the only thing you have to do is remember to carry it with you. For this reason I chose to use it for my recent studies which were filmed by BBC Horizon (planned broadcast Autumn 2013). I have been asked about the accuracy of the Zip given how much it must be optimizing in order to make the battery last so long, so I asked one of my participants to wear both on her waist at the same position for 2 months. This person is a 52 year old female with an office-based job but a relatively active life (as you can see from the raw data on the spreadsheets) and a personal determination to always get at least 10,000 steps every day. As you can see from the data, over 59 days the overall difference in step count was 3% (note: you can see some higher variations on certain days in the history because she travelled to the US and for some days at the beginning and end of the trip one fitbit was in the wrong time zone).
Now the time to charge the FitBits which require charging is at least half an hour and both myself and participants in my earlier study have forgotten it on the charger at times and thus missed out data. With the Zip you only need to remember to put it in your pocket at the beginning of the day and when you get the low battery warning email 2-3 months later to change the battery. As a result, for the insignificant accuracy difference I prefer the Zip.
In my next post I’ll compare the Zip, the wristband based FitBit Flex and the iPhone app Moves.