ElasticsearchBM25 - Part 3: Considerations for Picking b

Posted 2021-06-06 九师兄

This is the final post in the three-part Practical BM25 series about similarity ranking (relevancy). If you\'re just joining, check out Part 1: How Shards Affect Relevance Scoring in Elasticsearch and Part 2: The BM25 Algorithm and its Variables.

Picking b and k1

It’s worth noting that picking b and k1 are generally not the first thing to do when your users aren’t finding documents quickly. The default values of b = 0.75 and k1 = 1.2 work pretty well for most corpuses, so you’re likely fine with the defaults. More likely