Socially Optimum Output (MSB = MSC)
Market Failure: Externalities and Common Pool Resources
AO2·AO4·Diagram required
Syllabus requirement
Defines allocative efficiency where marginal social benefit equals marginal social cost, maximizing social/community surplus.
Assessment objectives
AO2 Application and AnalysisAO4 Use of Appropriate Skills
Required diagram: Diagram showing MSB = MSC at the socially optimal quantity, indicating allocative efficiency and maximum community surplus.
Summary
Socially optimum output is the level of production where marginal social benefit equals marginal social cost (MSB = MSC). At this point allocative efficiency is achieved because the last unit's benefit to society equals its cost, maximizing community surplus. When markets face externalities, private decisions diverge from the social optimum, causing welfare loss and providing a rationale for possible government intervention.
