Evaluating Machine Translation with BLEU

Learn to determine the performance of machine translation using the BLEU method.

We'll cover the following

Geometric evaluations
Applying a smoothing technique
- Chencherry smoothing

BLEU provides a method to evaluate candidate translations produced by machine translation models.

Papineni et al. (2002) came up with an efficient way to evaluate a human translation in the paper "BLEU: a Method for Automatic Evaluation of Machine Translation."The paper can be accessed at: https://aclanthology.org/P02-1040.pdf In this paper, they named their method the Bilingual Evaluation Understudy Score (BLEU).

BLEU is a French word for ‘blue’

The human baseline was difficult to define. However, they realized that we could obtain efficient results if we compared human translation with machine translation, word for word.

In this lesson, we will use the Natural Language Toolkit (NLTK) to implement BLEU.

We will begin with geometric evaluations.

Geometric evaluations

The BLEU method compares the parts of a candidate sentence to a reference sentence or several reference sentences.

The program imports the nltk module:

Get hands-on with 1200+ tech skills courses.

Course Introduction

Basics of Transformers

Architecture of the Transformer Model

Fine-Tuning BERT Models

Pretraining a RoBERTa Model from Scratch

Downstream NLP Tasks with Transformers

Machine Translation with the Transformer

The Rise of Transformers with GPT-3 Engines

Applying Transformers for AI Text Summarization

Matching Tokenizers and Datasets

Transformers for NLP—Exam 1

Semantic Role Labeling with BERT-Based Transformers

Your Data Speaks: Story, Questions, and Answers

Detecting Customer Emotions to Make Predictions

Analyzing Fake News with Transformers

Interpreting Black Box Transformer Models

From NLP to Task-Agnostic Transfomer Models

The Emergence of Transformer-Driven Copilots

Transformers for NLP—Exam 2

Conclusion

Appendix

Evaluating Machine Translation with BLEU

Geometric evaluations