IB Economics SL Internal Assessment Example

Includes three relevant diagrams that are clearly intended to model the sugary-drinks tax and the associated market failure.

Uses appropriate labels such as MPB, MSB, MPC/MSC, price, quantity, and welfare loss.

Provides a meaningful explanation of how the diagrams show overconsumption and how a tax can reduce quantity consumed.

The tax diagram contains a substantive error because it treats MSC as changing to MPC + tax, which is not accurate for a negative consumption externality.

The tax-incidence diagram is not fully consistent with the written analysis about elasticity and who bears the larger burden.

The explanations are helpful but not fully accurate, so the diagrams do not meet the highest standard for correctness and interpretation.

Uses a wide range of relevant economic terminology, including indirect excise tax, demerit good, negative externality of consumption, MPB, MSB, MPC, MSC, deadweight loss, allocative efficiency, and price elasticity of demand.

Terminology is generally integrated into the argument rather than listed in isolation.

Several terms are used effectively in relation to the article’s policy context and the intended market intervention.

Some important terminology is used imprecisely, especially around the relationship between MSC, MPC, and the tax.

The discussion of asymmetric information is not clearly developed as a separate market failure.

A few terms are not consistently aligned with the rest of the analysis, which weakens precision across the commentary.