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Delve into the search for the elusive Holy Grail of index number theory, exploring classical and alternative approaches, ideal indices and indicators, and recent contributions to the field.
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Searching for the Holy Grail of Index Number Theory Bert M. Balk Statistics Netherlands and Rotterdam School of Management Erasmus University Washington DC, 14 May 2008
The Holy Grail • … that is, • a symmetric pair of price and quantity indices that satisfy all known requirements, • … does not exist.
Classical index number problem • Decompose the aggregate value ratio into two parts • V1/V0 = P(p1, q1, p0, q0) × Q(p1, q1, p0, q0). • When Q(p1, q1, p0, q0) = P(q1, p1, q0, p0) then the indices are called ideal.
Alternative problem • Decompose the aggregate value difference into two parts • V1 - V0 = P(p1, q1, p0, q0) + Q(p1, q1, p0, q0). • When Q(p1, q1, p0, q0) = P(q1, p1, q0, p0) then the indicators are called ideal. • Go from additive to multiplicative decomposition and vice versa by logarithmic mean.
Ideal indices and indicators • Fisher indices • Montgomery-Vartia indices (correspond to Montgomery indicators) • Sato-Vartia indices • Stuvel indices • Bennet indicators
A recent contribution • Steve Casler, J. of Economic and Social Measurement 2006, developed a new decomposition. • Defects of these indices: • Not globally monotonic; • Not linearly homogeneous; • Fail time reversal test.