ML：关联规则之简单介绍

Explanation of the Market Basket Model

Definition：

1. List item

It is a rule-based machine learning method for discovering interesting relatiosn between varianbles in large databases. It is intended to identify strong rules discovered in databases using some measures of interestingness.

Usefule Concept

• $supp(X)=\frac{X}{Total}$
  support: is an indication of how frequently the itemset appears in the dataset;
  The support of X with respect to T is defined as the proportion of transactions in the dataset contains the itemset X.
• $conf(X=>Y)=\frac{X\cap Y}{X}=\frac{supp(X\cap Y)}{supp(X)}=P(Y|X)$
  Confidence: The confidence value of rule, X=>Y, with respect to a set of transactions T, is the proportion of the transactions that contains X which alse contains Y.
• $lift(X=>Y)=\frac{(\frac{X\cap Y}{X})}{(\frac{Y}{Total})}=\frac{supp(X\cap Y)}{supp(X)\ast supp(Y)}$
  Lift = 1: two events are independent of each other.
  Lift > 1: the degree to which those two occurrences are dependent on one another, and makes those fules potentially useful for predicting the consequent in future data sets.
  Lift < 1：无效的关联规则。

例子：

例如我们有如下数据：
则有

Practical Application of Market Basket Analysis

A list of applications of Market Basket Analysis in various industries is listed below:

• Retail. In Retail, Market Basket Analysis can help determine what items are purchased together, purchased sequentially, and purchased by season. This can assist retailers to determine product placement and promotion optimization.(商品摆放)

• Telecommunications. In Telecommunications, where high churn rates continue to be a growing concern, Market Basket Analysis can be used to determine what services are being utilized and what packages customers are purchasing. They can use that knowledge to direct marketing efforts at customers who are more likely to follow the same path.（组合套装）

• Banks. In Financial (banking for instance), Market Basket Analysis can be used to analyze credit card purchases of customers to build profiles for fraud detection purposes and cross-selling opportunities.

• Insurance. In Insurance, Market Basket Analysis can be used to build profiles to detect medical insurance claim fraud. By building profiles of claims, you are able to then use the profiles to determine if more than 1 claim belongs to a particular claimee within a specified period of time.

• Medical. In Healthcare or Medical, Market Basket Analysis can be used for comorbid conditions and symptom analysis, with which a profile of illness can be better identified. It can alse be used to reveal biologically relevent associations between different genes or between environmental effects and gene expression.