Wis. Stat. § 63.09
The director of personnel, under the direction of the commission and with the advice of the heads of the departments involved, shall devise and introduce as rapidly and extensively as practicable a system of efficiency records to be based, among other things, upon the quantity and quality of the work performed and the regularity and punctuality of attendance. After such system is introduced, the various departments thereby affected shall maintain it. The director of personnel shall also, under the direction of the commission, prepare a classification of subordinate positions in accordance with their natural tendency to fit their incumbents to fill higher offices or positions in the service of the county. The commission shall provide in its rules that the efficiency records of an employee in one of the aforesaid lower positions shall be given due weight in the examination of such employee for higher offices or positions to which they naturally lead, to the end that such higher offices or positions in the service shall be filled as far as possible by promotion.
Wis. Stat. § 63.09