âº EVC System. A disabled refuge is a relatively safe area within a building or exit staircase for mobility impaired occupants, allowing building management and emergency services to safely assist these people from the building.
Standard deviation is a number used to tell how measurements for a group are spread out from the average (mean), or expected value. A low standard deviation means that most of the numbers are very close to the average. A high standard deviation means that the numbers are spread out.
The standard deviation for a discrete variable made up of n observations is the positive square root of the variance and is defined as: Use this step-by-step approach to find the standard deviation for a discrete variable. 1  Calculate the mean. 2  Subtract the mean from each observation.