Design a better water bottle and test it

Come up with 10 distinct, non-overlapping design enhancements for a reusable water bottle built for commuters—such as insulation, grip, cap mechanism, filter, materials, volume markings, ergonomics, leak-proofing, cleaning ease, and accessories. For each one, provide: the intended user segment, a hypothesis, one key success metric, and an A/B or multivariate experiment with the unit of randomization, a rough power/MDE calculation, expected duration given today's date of 2025-09-01, risks such as novelty and seasonality, and stopping/rollback rules.

Overview: The question tests experimental design, product analytics, hypothesis creation, metric choice, sample size/power/MDE estimation, segmentation, and risk and rollback planning in the Analytics & Experimentation area for Data Scientist positions.

See the complete interview account for the Data Scientist role this question is drawn from.