Employees unionize to obtain outcomes that they believe they are unable to obtain as individuals. Member desires have a major impact on union bargaining goals. It has been suggested that contract demands reflect the preferences of the "median voter" in a unit,' thus requiring that the contract be acceptable to at least a majority to be ratified. Local union officers are often elected by a single bargaining unit. Bargaining success directly influences their ability to be reelected. Where local unions service several bargaining units, local officers might be less concerned about the content of individual contracts
Unions demonstrate their effectiveness by negotiating contracts that improve employment conditions for their members, attract new members, and organize additional units. As an institution, the union desires security as the employees' representative through negotiated union shop agreements.