Be warned an establishing shot and a master shot are not the same. Granted they were compiled as one discrete category due to the framing and composition being usually the same for both of them.
An establishing shot is a shot which introduces a new location such as a hospital room for example. This is performed from a vantage point that enables the audience to see all the relevant characters in the filmic space.
As for a master shot, a master shot would most probably be recorded from the same position, with the same lens and also showing all the same characters. The difference is the length. A master shot records the entire action, a complete run-through from that camera position. By doing so, if a tighter shot is forgotten during coverage, the director knows their editor will have enough material to show the scene in its entirety by cutting back to the master shot.
An establishing shot would not last no more than 10 seconds in the edited movie, while a master shot could last a number of minutes.