Association Rules

Some people call them “Related Selling” analyses. Others call them “Market Basket” analyses. Regardless of the name, association rules are used to examine the relationships that exist between the products you sell and the customers that buy them. These rules are typically expressed as probabilities, percents and likelihoods. For example, 10% of my customers buy Jewelry and Handbags, 50% of the customers who buy Denim also buy Polos, or Denim customers are 3.5 times more likely to buy Sunglasses than any of my other customers. The goal of the analysis is identify the co-occurrences of different products that happen with the greatest frequency. By performing this analysis you will be able to answer the questions posed above.

CustomerTool's association rules application analyzes POS transaction data to find the associations between the products your customers purchase. You do not need to be a statistician to use CutomerTool. All you need is access to the data. There is no hardware or special software to buy. Just upload your data and start getting answers.




Association Rules: An Example

CustomerTool produces 4 association rules: Expected Confidence, Support, Confidence and Lift. Each of these rules has a specific use in evaluating selling data. See the example below for a quick description of these rules.

Expected Confidence

Is the probability that any product you sell will be purchased by a customer. For example, a store had 100 customers today, and 20 of them purchased at least one shirt. Consequently, there is a 20% chance (EC) that any customer transaction will include a shirt.

Support

Is the probability that any combination of products you sell will be purchased by a customer. If 10 of the 20 customers who bought a shirt also bought a hat, then shirts and hats have a 10% chance (Support) of occurring together on any transaction.

Confidence

Is the probability that if a customer buys a product(s) they will also buy another. Using our example above, shirt customers have a 50% chance of also buying a hat (10/20).

Lift

Is expressed as a ratio and measures the likelihood of buying one product given that another product has been purchased. Lift is calculated by dividing Confidence by Expected Confidence. In our example, someone who buys a shirt is 2.5 times more likely to buy a hat than someone just walking in the store. NOTE: It is possible to uncover lifts less than 1. This means that the products are negatively correlated and actually make someone less likely to buy another product.

A graphical example

Links to resources on Association Rules

IBM Association Rule Mining
Oracle Association Rules
HP Association Rules on a Spherical Surface
Market Basket Analysis books sold on Amazon
SAS Enterprise Miner 5.2
SPSS Association Rules
Statsoft Association Rules
Stanford Association Rules
Megaputer
Hyperion
Marketing Power Market Basket Analysis Definition
BusinessWeek Article about Quantitative Marketing
Forbes Article on Market Basket Analysis
MIT Association Rules
Cornell Univeristy - Market Basket Segmentation
SAS Customer-Centric Approach
SF Gate Article