A Quadratic Almost Ideal Demand System Estimated with Pooled regional Time Series: Approximates Aggregation with an Accounting for Age, Cohort, and Trend Effects.
Starting with a theoretical QUAIDS model at the micro level, an approximate aggregation is developed that allows the model to be applied to time series at the macro level (The approximated aggregation holds for a "representative" consumer with utility equal to the harmonic mean of the individual consumers' utility.)