# Personalized Purchase Prediction of Market Baskets with Wasserstein-Based Sequence Matching

## TL;DR

This paper introduces a novel method for personalized purchase prediction using Wasserstein-based sequence matching, significantly outperforming existing decision rules in accuracy by identifying cross-customer purchase patterns.

## Contribution

It proposes a new predictor for market baskets based on subsequential dynamic time warping and Wasserstein distance, enabling better pattern recognition across customers.

## Key findings

- Outperforms state-of-the-art decision rules by a factor of 4.0 in accuracy.
- Uses Wasserstein distance to measure similarity among purchase histories.
- Develops a fast approximation algorithm for Wasserstein distance in this context.

## Abstract

Personalization in marketing aims at improving the shopping experience of customers by tailoring services to individuals. In order to achieve this, businesses must be able to make personalized predictions regarding the next purchase. That is, one must forecast the exact list of items that will comprise the next purchase, i.e., the so-called market basket. Despite its relevance to firm operations, this problem has received surprisingly little attention in prior research, largely due to its inherent complexity. In fact, state-of-the-art approaches are limited to intuitive decision rules for pattern extraction. However, the simplicity of the pre-coded rules impedes performance, since decision rules operate in an autoregressive fashion: the rules can only make inferences from past purchases of a single customer without taking into account the knowledge transfer that takes place between customers. In contrast, our research overcomes the limitations of pre-set rules by contributing a novel predictor of market baskets from sequential purchase histories: our predictions are based on similarity matching in order to identify similar purchase habits among the complete shopping histories of all customers. Our contributions are as follows: (1) We propose similarity matching based on subsequential dynamic time warping (SDTW) as a novel predictor of market baskets. Thereby, we can effectively identify cross-customer patterns. (2) We leverage the Wasserstein distance for measuring the similarity among embedded purchase histories. (3) We develop a fast approximation algorithm for computing a lower bound of the Wasserstein distance in our setting. An extensive series of computational experiments demonstrates the effectiveness of our approach. The accuracy of identifying the exact market baskets based on state-of-the-art decision rules from the literature is outperformed by a factor of 4.0.