Why is the median first reply time higher than the median full resolution time on my default Support dashboard in Explore?
This happens because those reports do not have the same date filter applied. The median First reply time report is filtered on the Ticket created - Date attribute, while the median Full resolution time report is filtered on the Ticket solved - Date attribute. As a result, these are not the same set of tickets that are analyzed in the two reports.
For example, say you set the time filter of your dashboard to Last week. The median First reply time computes all the tickets created last week, while the median Full resolution time computes all the tickets solved last week even if they were created before last week. The two reports cannot be compared directly.
For more information, see the article: Explore recipe: Getting to know dashboard filters.