IB Economics HL Internal Assessment Example

The student included two relevant diagrams that are clearly tied to the electricity-market externality in the article.

The student's first diagram shows a sound overall causal story from negative externality to overproduction and corrective taxation.

The diagrams are well integrated with the policy discussion, rather than being generic add-ons.

One or more diagrammatic details are not fully accurate or clearly bounded, especially around the tax-revenue rectangle and the post-tax price relationships.

The second diagram’s logic is not consistently clear, particularly the relationship between the tax and any shift in marginal social cost.

A brief, explicit explanation beneath each diagram would reduce ambiguity and make the visual argument easier to follow.

The student uses core economic terminology accurately and repeatedly, including MPC, MSC, external costs, welfare loss, and indirect tax.

The terminology is generally applied in context rather than just being defined.

The student also incorporates more advanced terms such as price elasticity of demand and internalization of external costs effectively.

A few expressions are slightly imprecise, especially around how the rebates are financed and described.

Some distributional phrasing should be tighter to avoid implying mechanisms that the article does not directly establish.