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EC311 · Intermediate Microeconomics

EC311 / TOPIC 40

10.2 Production efficiency and social welfare

How do production efficiency, output mix, and fairness differ?

Efficiency requires equal MRTS and MRS=MRT, while welfare criteria still choose distribution.

Follow the cause and effect

  1. Reallocate inputs until MRTS is equal across production.

  2. On the PPF, choose the mix where consumer MRS equals MRT.

  3. Separate efficiency from utilitarian or Rawlsian distribution.

The model you are using

KEY MODEL
MRTS₁=MRTS₂
MRS_A=MRS_B=MRT
Wutilitarian=U_A+U_B
WRawls=min(U_A,U_B)

Conditions for this model

Equalities apply to smooth interior allocations; interpersonal welfare calculations assume the comparability stipulated by the problem.

The exam trap

Being on the PPF ensures production efficiency, not an efficient output mix by itself.

Connect the reasoning to the graph

What changes

  • The PPF shows MRT as slope, while social indifference curves select a point based on distributional values.

What stays fixed

Equalities apply to smooth interior allocations; interpersonal welfare calculations assume the comparability stipulated by the problem.

Keep these conditions throughout the comparison; change only what the case above specifies.

What to inspect

Separate efficiency from utilitarian or Rawlsian distribution.

Compare before and after, and locate the conclusion on the graph.

5 MINUTES · TRANSFER THE IDEA

Can you explain it without the lesson?

Construct an example where utilitarian and Rawlsian criteria choose different points on a utility frontier.

Lesson references

  • Pindyck & Rubinfeld, Microeconomics, 9th Global ed., pp. 624, 627, 629–630
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