01 · E-commerce · £10m a year
A £10m increase in sales: serving 2.6 million additional customers
- Client
- E-commerce
- Service
- AI Engineer · Recommendations
- Focus
- Cold-start coverage
- Stack
- Python · PyTorch · TorchRec · Databricks · Airflow · SageMaker
In brief
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 challenge
The users who needed help most got the least
The recommender learned only from people with an established history, so a large group of newer users saw generic results. The obvious move — lower the threshold — carries a real risk: bringing in users with less history can degrade recommendations for the high-value users already being served well. The change had to hold performance for existing users while improving activation for new ones.
The approach
Widen the funnel, guard the baseline
Halving the threshold moved five cohorts into personalised results. The four already above it were unchanged.
Before
After
The results
£10m
Additional annual sales, driven by new users moved onto personalised recommendations.
+2.6m
Users brought into personalised recommendations, around 50,000 more each week.
+12.4%
Return rate among those new users — they come back more often as well as buy.