In Google Analytics, a Property is a website, mobile application, blog, etc., that is associated with a unique tracking ID. One Google Analytics Account can contain multiple Properties. Learn more about Google Analytics Properties here.
When the number of Sessions tracked in a single Property exceeds 500k for the selected Date Range, Google Analytics may apply Session Sampling to your data to produce an accurate representation of your data in a shorter amount of time. Learn more about Sessions Sampling here.
Session Sampling happens in some, but not all cases that meet this criteria. Because of that, you may see what appears to be partial data when comparing data between Google Analytics and Databox. This happens when you're viewing a complete data set in Databox against a sample data set in Google Universal Analytics, or vice versa.
If the data in your Google Analytics Account is being sampled, you'll see the following message on your report:
In Databox, Sampling is only applied to select Custom Metrics where you've applied a Segment, Filter or secondary Dimension. Learn more about the Metric Builder for Google Universal Analytics here.