Find the perfect frequency of newsletters per week, and optimize your email marketing strategy.
Find out if free goods in each order actually help retention or if it's just another cost.
See if offering 1-day delivery actually boosts retention or if it's just another cost burden.
Turn off advertising to your most loyal customers and see if you can save marketing spend.
Find the impact that discounts have on retention and winning back customers.
Turn off advertising to a select amount of customers and see if your advertising actually impacts sales.