ocr: ransactioniFact a - . Product Product key Store dimension mension: sorear Ke) Customer key Customer. Sales ticket Salesticket_key dimension dimension Hme key nme Quantity.sold dimension Dollars sold Figure 1. A typical star join schema for a set of retail sales trans- actions. Each fact table record is a line item on a particular customer ticket. In this article, I show how to add a sixth " causal" dimension that explains why the sale took place.