# Lessons Learned

This chapter looks at what customers purchase, rather than when or how they purchase, with an emphasis on exploratory data analysis. The contents of market baskets can be very interesting, providing information about both customers and products.

A good way to look at products is by using scatter plots and bubble charts to visualize relationships. A useful Excel trick makes it possible to see products along the X- and Y-axes for bubble charts and scatter plots.

Investigating products includes finding the products associated with the best customers, and finding the ones associated with the worst customers (those who only make one purchase). It is also interesting to explore other facets of products, such as the number of times a product changes price, the number of units in each order, the number of times products are repeated within an order, and how often customers purchase the same product again.

Exploratory data analysis goes beyond just these questions. Pricing is a...