To adjust for incorrect device clocks, one approach is to log three timestamps [82]: The time at which the event occurred, according to the device clock The time at which the event was sent to the server, according to the device clock The time at which the event was received by the server, according to the server clock By subtracting the second timestamp from the third, you can estimate the offset between the device clock and the server clock (assuming the network delay is negligible compared to the required timestamp accuracy). You can then apply that offset to the event timestamp, and thus
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