The total staff population of any structure is the entire number of persons currently holding jobs or working positions which are based primarily within that structure. For this number successive shifts in the same position are counted individually, so that the number may be far greater than the number working in the structure at any one time. This number counts management personnel as well as employed persons. It does not count persons working from home in a residential building.

A staff count applies to a particular time and needs its source and reference date. Counts from different years can reflect changes in staffing; the difference alone does not establish whether either count is correct.

Total staff population includes people on successive shifts, as described above. It can exceed the number present at any one time and cannot be used as a measure of simultaneous occupancy or full capacity.

Residential population and staff population count people through different relationships to the building. Any combined count needs to account for overlap and for the working-from-home exclusion stated above.