Use the objective, the evidence and the alternative.
A useful judgement connects the policy mechanism to a specific objective, then checks who gains, who loses and what limits the result. Compare a feasible alternative, account for time and budget, and distinguish an observed change from evidence that the policy caused it. End with a condition that would change your recommendation.
- Mechanism
- Explain how the instrument could achieve the objective.
- Evidence
- Consider other changes that could explain the outcome.
- Judgement
- Choose a feasible policy with a stated condition for review.
Worked example: Affordable transport with limited capacity
A fare subsidy lowers a route's fare. Ridership rises, but services remain full at peak time. A new nearby housing estate also opens during the period.
- If the objective is affordability, lower out-of-pocket fares help riders who obtain a place. Ridership alone does not measure who could afford to travel.
- Crowding suggests capacity constrains access. More buses may improve access, but require vehicles, drivers and budget.
- The new estate could also raise demand, so the entire ridership increase cannot be attributed to the subsidy.
- Retain targeted fare support if cost is the main barrier; add capacity where missed boarding is substantial. Reassess using access by income, crowding and cost per additional trip.
Watch out for this
Evaluation is a list of advantages and disadvantages.
Weigh the relevant effects against the objective and evidence. State which consideration matters most in this context and why.
Check your understanding
A tax is followed by lower purchases during a recession. Which conclusion is justified?
- The entire fall was caused by the tax.
- The tax may have contributed, but the recession is another possible cause.
- The tax had no effect because another factor changed.