Recently, someone asked how the default values on Pricing Insights were determined. They were referring to these boxes at the top of the dashboard.
When the dashboard first loads, a median sold price is calculated based on the selected filter criteria. You can see value is in the box on the lower right side of the dashboard below the gauges.
That median sold price is used to populate the Proposed List Price box. The Total Square Feet box is populated with the median square feet of the listings specified by the filter.
Note that the default values are populated with only the first completed query. That means if you select one town and the dashboard starts its refresh, but then you add another town before hiding the filter panel, the default value won't match the median sold price box. That's okay! You're meant to use those boxes to put in your own proposed price, which then won't change as you change filters.