Step counter value '0' possibly ambiguous

[CookieFactory]

Dear community,

We are using Fitbits for our cardiovascular research and I have a question about how the step counter reports value 0 (zero).

It has come to my notice that there is a difference in reporting zero steps between step counter data acquired from the Fitbit Web API and doing a raw Data Export (by going to https://www.fitbit.com/settings/data/export and clicking on 'request data' at the bottom section "Export Your Account Archive"). The web API always reports steps per minute while the Data Export does not report steps for every minute. Before clarifying my issue with this please see an example of the two sources using my own account:

This is a snippet from the raw Data Export:

{
  "dateTime" : "01/26/20 15:07:00",
  "value" : "0"
},{
  "dateTime" : "01/26/20 15:10:00",
  "value" : "17"
},{
  "dateTime" : "01/26/20 15:11:00",
  "value" : "0"
},{
  "dateTime" : "01/26/20 15:14:00",
  "value" : "18"

This is the same date and  same time range(time zone corrected), but obtained through the Fitbit web API

{"time": "15:07:00", "value": 0},
{"time": "15:08:00", "value": 0},
{"time": "15:09:00", "value": 0},
{"time": "15:10:00", "value": 17},
{"time": "15:11:00", "value": 0},
{"time": "15:12:00", "value": 0},
{"time": "15:13:00", "value": 0},
{"time": "15:14:00", "value": 18},

 As you can see, the raw Data Export does not report steps for all minutes, which I interpret as a 'missing value'. In addition, it contains minutes with 0 (zero) steps. However, according to the fitbit web api, what was missing in the raw data export now also have value 0. Thus, through the Fitbit web API it is now ambiguous whether value 0 means 'missing value'  above or if it is actually 'zero steps'.

Could a developer please elaborate? Is it indeed ambiguous or does the raw data export simply not report most minutes with zero steps? Can I safely assume that 0 steps in the fitbit web api is really 0 steps, despite its misleading difference with the raw data export?

Thank you very much

[Gordon-C]

Hi @CookieFactory 

The Raw Data export and the Web APIs use 2 different methods for exporting the data.   The Web APIs are designed to return the data every minute.  When step data doesn't exist (meaning no steps are recorded), we return a zero.   Based on your raw data export report, it looks like it is sampling the results when steps = 0.   What should be important is the recorded steps each minute and the total step count are the same.

Gordon

[CookieFactory]

Hi Gordon,

Thanks for verifying and agreed that recorded steps each minute should add up to total step count. 

However, I do really think it is valuable to distinguish the situation where the step counter is not recording (i.e. device is not worn) or someone is sitting still. I suppose this cannot be distinguished by the accelerometer alone (PPG sensor can do this because it is easy for it to check whether it is making contact with your wrist).

Thanks again,

Arman