Timestamp in local or UTC time?

[larsen....@gmail.com]

Hi! Looking at the statistical data collected centrally by the
Mnemosyne Project, [1] is there any way to find the local time
at which a user reviewed a particular card? So far as I can tell
(correct me if I’m wrong), the timestamp stored for each row is
in UTC.

Cheers,


Tom.


[1] E.g. https://archive.org/details/20140127MnemosynelogsAll.db,
thanks to Gwern.

[Peter Bienstman]

Hi,

The timestamp is in local time. The next rep is however stored as midnight UTC to represent just a date as opposed to a date and time.

Cheers,

Peter

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[larsen....@gmail.com]

Hi Peter!

I’ve been doing some analysis on the research dataset.
There’s something which is kinda disconcerting about it,
however: if the timestamp is always in local time, it seems
that more card reviews are performed around 2–3 am than in
the afternoon and evening hours... somehow that doesn’t
seem especially plausible.

Summary:

http://i.imgur.com/DBrUapx.png

Analysis:

https://gist.github.com/anonymous/6b6304493adf2008fef2

I’ve probably gone wrong somewhere,
but it would be helpful to know where.

Cheers,


Tom.

[Peter Bienstman]

Oops, seems I remembered wrong: I looked back into the code and ththe timestamp is calculated by time.time()
https://docs.python.org/2/library/time.html

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[larsen....@gmail.com]

Hi Peter,

Thanks for your quick response! :)

It seems that an unfortunate consequence of this is that
the present research dataset can’t yield interesting results
on users’ memory performance based on time of day. That’s sad,
because I think this is one area in which I think a lot of
excellent research could be conducted in the future!

I wonder if it would be possible to:

1. Change Mnemosyne so it uploads local time rather than UTC
to the research server. (If timezone information could also
be uploaded, that could also make for an interesting research
project sometime down the track.)

2. Archive the current research database and begin a new one
afresh using the local time information instead (otherwise
the statistics will be skewed significantly based on the
old UTC time data), requiring users to upgrade before their
log data will be uploaded.

Thanks again!


Tom.

[Peter Bienstman]

Hi,

In hindsight, that was indeed not such a good decision. I think the best way to rectify this without invalidating the old data is simply to also log the timezone of the users. Once we know the timezone of a user, we can also reinterpret the old logs.

Cheers,

Peter

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[larsen....@gmail.com]

Hi Peter,

That sounds like the best course of action
(assuming that no really prolific user has
moved timezones in the past).

Thanks very much! :)


Tom.