Are Aggregate Scanner Data Models Biased?
Ross Link president, Marketing Analytics, Inc
Much heat and little light has been shed on the issue of whether or not store-level data is required in order to accurately estimate scanner-data price, promotion, and marketing-mix models. The major data suppliers' modeling groups say store-level data is required because of an effect called 'aggregation bias.' This paper discusses aggregation bias and tests done on its impact. It turns out that the suppliers' claims are about half true. Aggregation bias is real and should be avoided, but store-level data is not required to do so....