GPS Data is not accurate

Hi! I am using GPS data for a test run of a study. I have had the app opened on my iPhone and have recently exported my data after 3 days. I see that my GPS coordinates did not collect the data accurately as I know I was travelling around the city in the past 3 days. The study is 1269 and I am participant 28491. All the GPS data shows that I have not left my home in 3 days. Please help, I need the GPS data to be accurate for this study.

Hi @mdtang

When you say the data was not collected accurately, do you mean:

A. You do not have data for the entire 3-day data collection. There are some hours that have data, but for some hours there is no data.
B. Or, you mean, for a given hour, the collected data does not properly presents the location you were at. For example if you were at coordinates (X,Y), the collected data shows this with a large noise.

Can you clarify which of these you mean?


Hi @m.hashemian,

Option B! I know that I was in different locations through out the three days and the GPS coordinates are showing a cluster in one area (my apartment).


Thanks @mdtang. Can you tell me a time window which you were at a different place than what the data shows? I need to take a look at the logs and see if I can find the cause of it.


The time window specifically would be for a day, Monday July 20th, at 12-1pm and from 3-10pm I was in a different location.


@m.hashemian sorry forgot to tag you

@m.hashemian hi has there been any update to what has been happening?

Hi @mdtang Sorry for the silence. What’s happening is that Ethica uses an algorithm to detect if the person has moved since the last time it collected GPS, or whether the person has been just stationary. And if the person has been stationary, the app does not collect GPS and simply reuses the last GPS readings. In your case, in all the cases you listed, the app assumed you have not moved much, even though you did actually move.

So we had to perform some further tests to see why this issue had happened. We found the issue in our algorithm, fixed it, and are now testing it. We expect to roll out an update before this weekend. Then you can run another test and this time you should get the proper data.

Thanks a lot

Thank you @m.hashemian, please let me know when you will be done testing!

Hi @mdtang

We updated the app with the necessary fix. If you update your iPhone app to the latest version (352), you should be able to get accurate GPS readings (the update might take a few hours before it becomes available through the Apple’s App Store).

Thanks again for reporting this issue