This is a list of the advantages your staff members give when assigned to one of your facilities. The bonuses increment linearly from a skill 1 staff (minimum) to a skill 10 staff (maximum).
You can see the exact bonus for a facility on the overview page of that facility.
A staff member in the office will let you assign a second staff member to one of your other offices. This second staff member will give the same bonus on top of the first bonus. For example, two staff members with 20% bonus will give a total bonus of 44% (1.2*1.2 = 1.44)
You still can have only one staff member assigned per level of the office, so you need an office of at least level 3 to take advantage of this. You can not assign a second staff member to the office.
In addition, the office staff member will reduce the wages you pay to all of your staff members. This starts from a reduction of 2% at skill 4 to 20% at skill 10. Skill 1-3 gives no bonus other than the extra staff member in another facility.
Your stadium staff member will give an attendance bonus of 6% up to 15% and will make you sell 20 to 200 seats more per ticket sold.
A staff member in the training complex will give your players 3.7 to 10% extra training experience points.
In addition, special training will be 5.5 to 15% faster.
In comparison: improving the training complex from level 9 to level 10 will give a 11% bonus on both training xp and special training time.
The youth center staff member will make your player 9 to 27 weeks younger and add 0.4 to 1.5 balls of speed, power or endurance (distributed randomly).
The normal random generation of the new player still applies so it's still possible for the players to be worse than a luckier draw from a facility without staff but on average they will be better.
A staff member in the fanshop makes your club lose their fans 6 to 15% slower. It also increases the fan conversion to better fan types by 6 to 15%.
This bonus is relative to the normal values, not absolute. For example, a level 6 fanshop converts 0.083% of casual fans to normal fans every day. With a staff member of 10 skill this becomes 0.083%*1.15=0.09545%.
A staff member in the health center reduces the match fatigue by 7.5% to 30% and reduces the injury time after treatment to 86% to 40% of the normal time after treatment.
The injury reduction is applied after normal treatment. For example, take a health center level 7 would reduce injury time of 8 days by 45% to 4.4 days (8*0.55). With staff level 4 (70%) the injury time is reduced to 4.4*0.7=3.08 days. With two staff members of level 10 (40%), the injury time is reduced to 4.4*0.4*0.4=0.704 days
With a staff member in the scout office you get 2 to 20 extra free analyse reports. You also need to pay 2 to 20% less credits for created players.
The staff member in the catering will increase income of this facility by 38 to 110%
From season 33 this bonus only applies for league matches to make it more equal for all teams.
The staff member in the museum will increase income of this facility by 5 to 50%. It also decreases the building time for the museum by 5 to 50%.
Two 10-skilled staff members in the museum can reduce the construction time to 25%
The construction master is a staff member that is not assigned to any particular facility, but it follows the same rules as any other staff type.
This staff member reduces the building time for your facilities by 3% per level. From 3% for a level 1 construction master to 30% for a level 10 construction master.