Hi all!
We have just finished a baseline survey using ODK, and going through the
exported data I have come across an issue with date stamp inaccuracies:
I used "start" and "end" at the beginning of the survey form to
automatically date/time stamp the survey, as well as the calculate date
function. There are 2 instances in which all of the surveys collected at 2
different schools (a total of 29 and 40 surveys, respectively) are stamped
with a date before data collection even began-- not the date which the data
were reportedly collected. All of these surveys were collected using the
same phone, by the same enumerator.
The fieldwork manager has checked the phones and confirmed that the current
date is programmed in the phone correctly. Does anyone have advice/insight
as to what may cause the date to be incorrect?
Thanks in advance for your help!
Best,
Anna
The date is obtained from the system clock on the device.
I don't know if it can happen on a tablet/phone, but on PCs, if you drain
the battery, and don't recharge quickly, the clock time can be wrong (set
to a random value, the last value it had, or Jan 1, 1970) when you next
power up the PC. It only gets corrected / reset to the correct time when a
connection to a wifi or cellular network is made, or, in some cases, if a
GPS location is captured.
Therefore, if you were to collect data without first contacting a server or
accessing the wifi or cellular network, you could have start and end times
that are incorrect.
This is one reason why recording the deviceID is useful -- it allows you to
identify surveys from the same device that may need to have systematic
corrections applied to them.
···
On Wed, Jan 7, 2015 at 8:35 AM, wrote:
Hi all!
We have just finished a baseline survey using ODK, and going through the
exported data I have come across an issue with date stamp inaccuracies:
I used "start" and "end" at the beginning of the survey form to
automatically date/time stamp the survey, as well as the calculate date
function. There are 2 instances in which all of the surveys collected at 2
different schools (a total of 29 and 40 surveys, respectively) are stamped
with a date before data collection even began-- not the date which the data
were reportedly collected. All of these surveys were collected using the
same phone, by the same enumerator.
The fieldwork manager has checked the phones and confirmed that the
current date is programmed in the phone correctly. Does anyone have
advice/insight as to what may cause the date to be incorrect?
Thanks in advance for your help!
Best,
Anna
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Mitch Sundt
Software Engineer
University of Washington
mitchellsundt@gmail.com
Thanks so much for your prompt reply, Mitch!
This makes a lot of sense... the data were collected in very remote
locations that did not have cellular network connections.
Best,
Anna
···
On Wednesday, January 7, 2015 11:35:46 AM UTC-5, anna.n...@gmail.com wrote:
>
> Hi all!
>
> We have just finished a baseline survey using ODK, and going through the
> exported data I have come across an issue with date stamp inaccuracies:
>
> I used "start" and "end" at the beginning of the survey form to
> automatically date/time stamp the survey, as well as the calculate date
> function. There are 2 instances in which all of the surveys collected at 2
> different schools (a total of 29 and 40 surveys, respectively) are stamped
> with a date before data collection even began-- not the date which the data
> were reportedly collected. All of these surveys were collected using the
> same phone, by the same enumerator.
>
> The fieldwork manager has checked the phones and confirmed that the
> current date is programmed in the phone correctly. Does anyone have
> advice/insight as to what may cause the date to be incorrect?
>
> Thanks in advance for your help!
>
> Best,
> Anna
>