ABSTRACT
The problem dealt with in this paper can be outlined simply. Assume we wish to compare the performances of a linear disaggregated versus a linear aggregated model in predicting the aggregated variable Y1 = ∑yit . Assume further that at the disaggregated level the following model has been specified, estimated, and (successfully) tested https://www.w3.org/1998/Math/MathML"> y i t = a x i + i t u i t https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315822549/a1c36de0-fe94-4936-be4b-07495fc3034a/content/math_65_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
