Data Mining Methods to Link Multiple Drug Purchases and To Investigate Drug Costs to Consumers

When one field is used to define the observational unit in a dataset, it becomes difficult to alter the dataset to define a different observational unit. For example, customer drug purchases are usually defined by the purchase rather than by the customer. The Association Node in Enterprise Miner uses a customer identifier to link purchases when the purchase is the observational unit. However, the Association Node is inadequate when there are too many different choices for purchase. An alternative method is to change the observational unit to the customer using PROC TRANSPOSE and PROC CONCAT. In this way, all customer purchases are linked in a text string that can be examined using SAS Text Miner. A second method is to reduce the number of choices by defining larger classes that combine choices that are relatively similar. The methods demonstrated in this paper will be applied to a public dataset similar to those collected in any retail pharmacy.