My tracker, my network and my server all disagree on what day it is

Scripts & SEO
1

spent an embarrassing amount of yesterday chasing a discrepancy that turned out to be nothing but timezones. my tracker logs in utc, the ad network reports in whatever their office clock is, and my server was set to local, so my monday numbers were three different mondays.

once i lined the reporting windows up the gap i was panicking about mostly vanished. posting it because i doubt im the only one who has burned hours on this. how do you keep the clocks honest across tools you dont control, do you just force everything to utc and do the mental conversion, or is there something smarter?

2

Everything i own is forced to utc, server, tracker, database, all of it, and i only convert to local at the very last step when a human looks at a chart. The tools you dont control are the problem, and the fix is to never compare their raw dashboard to yours directly. Pull their data by their day boundary, pull yours by yours, and reconcile on a rolling window instead of a single calendar day. One day will never tie out across three systems, a seven day total almost always will.

3

i lose half a day to this exact thing last month. the network say one number, my log say another, i think someone is shaving me, but no, it was only the day cut at a different hour. now i write the timezone next to every report in my sheet so i dont forget which monday is which. small habit, it save me from the panic.

4

The nastier version of this bites you in split tests. If your variant split happens on a different clock than your conversion logging, your morning traffic and your evening traffic land in the wrong buckets and a result looks significant when its really just the clock. I align every test to one timezone before i trust a single number off it. Learned that after calling a winner that was really the timezone deciding which half of the day went where.

5

This is the rule on the ad stack too. Every adserver and partner i deal with reports on its own cutoff, and some of them quietly shift it with daylight saving while your server does not, so twice a year everything breaks for no reason anyone remembers. I keep a tiny note of each partners reporting timezone and dst behaviour next to their line in the reconciliation sheet. Boring, but it is the difference between a real discrepancy and a clock.

6

fwiw i hit the same thing on my end and assumed for a day someone was ripping me off before i realised it was just the clock. the fix that stuck was writing the timezone in the column header of every sheet so i cant forget which day boundary im looking at. not clever but it stopped me chasing ghosts. forcing the server to utc helped too, one less moving part lying to me.