Principles:Qualification and Control/en/
Minimum worker requirement
Minimum worker requirementis a rounded number. If it says it needs ~24 workers, the actual number of required workers can vary from 23.6 to 24.4 which is why 24 isn't always enough for 100% efficiency. Hiring 1 worker more than the minimum seems to be enough so long as more workers won't be needed due to additional customers being attracted or subdivision workers being hired during the upcoming fame week.
(Data needed on this stat since it does not seem to relate to workers required for an office. Perhaps it's related to having large numbers of subdivisions with low amounts of employees in each? It seems so, 1 subdivision with a single employee under an office with 2 office workers has an admin load of 24%, while they could be managing up to 20 employees)
Efficiency of staff in relation to management qualification
Staff efficiency is based on 3 primary factors. Their quality (affected by wages and training) compared to the quality required. The quality of their equipment compared to the requirement. And finally the efficiency level of the office which is in control of the factory/store. A factory with less than maximum number of employees will still be considered working at 100% efficiency. However, it will be working under maximum capacity which is a requirement for a level two quest.
Offices are slightly different. Not only do they require equipment and staff quality to be in line, but they must also be able to meet up with the work load. More employees in the controlled subdivisions put a greater work demand on an office and can lower the efficiency. In an office however, the control quality (which for all other businesses is determined by the controlling office efficiency) is directly tied to the player's management qualification.
Through trial and error (more confirmation needed - Foarl Apr. 17, 2010), it seems that a player can control 10 office employees per level of qualification. Therefore a new player can only have 10 office workers at 100% efficiency, while a level 3 management can have up to 30 office workers working efficiently. It does not matter if these workers are split up over different offices or not. Furthermore, each office worker at 100% efficiency allows for the management of 100 employees in controlled subdivisions. Effectively, you can have 100 workers in controlled subdivisions per level of management skill.
Management qualification increases based on the number of workers you control in offices. The stat can be increased very rapidly by hiring extra office workers over the allowed limit at a hideous cost to productivity. One example would be that hiring 70 office workers at level 3 management caused the gain of 0.5 management level in one day, but at the cost of reducing main office efficiency to 8% (which cut down all subdivision efficiency to a maximum of 20%, which affects both sales and factory production). It is unclear if this cost is worth sacrificing on purpose to help get a faster start on management skill.
Administration Load Administration load seems to be based off the number of subdivisions controlled by an office, as well as the volume of advertising that the office has to deal with. More advertising campaigns and subdivisions can increase this beyond an offices administration abilities. It is possible this administration load maximum can be increased by marketing qualification, but no easy explanation is in sight.