Audit Trails, Time Zones and Timestamps

The following note may help our users who are reviewing REDCap logs and data trying to understand a sequence of events. This may be particularly helpful when auditing/monitoring a Health Canada study.

Audit Trails, Logging and Timestamps

• During data entry, data that is entered into a REDCap form is held locally in the browser and is not saved into the database until the user saves the form using one of the save options. (Save & Exit, Save & Stay, etc.)

• While performing data entry into a long form, a user may wish to save the form at intervals to ensure that data is not lost due to an unexpected interruption.

• REDCap creates log entries when a form is saved. The logging module will show all data changes that are made during a single save operation as a single log record.  However, the log record only provides information for new data and data that has changed. As a result, individual data items on the same form may end up with different timestamps. (The timestamps for individual data items can be viewed using the history widget on the form.)

Time Zones

• Data that is entered through a user's browser takes its time from from the browser. So, any date and times that appear in data collection fields on a REDCap form will be in the user's local time.

• Data shown in the REDCap logs and the history 'widget' take their time from the server.

• Our REDCap servers are hosted at the University of Alberta. The server clocks are set to the current time in Mountain Time.

So, for example, if a user in Ontario is performing data entry at noon local time and pushes the "now" button on a form, then the current time will be entered into the form as 12:00. If they immediately save the form that action will be logged in the REDCap logs as 10:00 since the timestamp on the server is Mountain Time, which is two hours behind Eastern Time.