A £10m increase in sales:serving 2.6 million additional customers
The client's recommender only learned from people with an established history, leaving a large group of newer users on generic results. We halved the threshold to pull them in, without diluting recommendations for everyone already there. The result, 50,000 more customers were served tailored recommendations each week, worth ~ £10m in additional sales per annum.
The users who needed help most got the least
The client's recommender only learned from people with an established history, leaving a large group of newer users on generic results.
The obvious move — just lower the threshold — carries a real risk. Bringing in users with less history can result in existing, high value users recieving less personalised recommendations. The change had to maintain performance for existing users whilst improving activation for new ones.