# Sales Demand Forecast in E-commerce using a Long Short-Term Memory Neural Network Methodology

## TL;DR

This paper presents a novel LSTM-based approach for E-commerce sales demand forecasting that leverages related product time series and hierarchical data to improve accuracy over existing methods.

## Contribution

The study introduces a unified LSTM model incorporating cross-series information and systematic pre-processing for improved E-commerce sales forecasting.

## Key findings

- Outperforms state-of-the-art techniques on real-world datasets.
- Effectively captures demand relationships in product hierarchies.
- Demonstrates robustness across different product categories.

## Abstract

Generating accurate and reliable sales forecasts is crucial in the E-commerce business. The current state-of-the-art techniques are typically univariate methods, which produce forecasts considering only the historical sales data of a single product. However, in a situation where large quantities of related time series are available, conditioning the forecast of an individual time series on past behaviour of similar, related time series can be beneficial. Since the product assortment hierarchy in an E-commerce platform contains large numbers of related products, in which the sales demand patterns can be correlated, our attempt is to incorporate this cross-series information in a unified model. We achieve this by globally training a Long Short-Term Memory network (LSTM) that exploits the non-linear demand relationships available in an E-commerce product assortment hierarchy. Aside from the forecasting framework, we also propose a systematic pre-processing framework to overcome the challenges in the E-commerce business. We also introduce several product grouping strategies to supplement the LSTM learning schemes, in situations where sales patterns in a product portfolio are disparate. We empirically evaluate the proposed forecasting framework on a real-world online marketplace dataset from Walmart.com. Our method achieves competitive results on category level and super-departmental level datasets, outperforming state-of-the-art techniques.