What are the common pitfalls that invalidate an A/B test?
Running an A/B test is easy; running a valid one is hard. What matters is naming the traps that produce confidently wrong conclusions and the fix for each. Here is the checklist a senior experimenter carries.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Running an A/B test is easy; running a valid one is hard. What matters is naming the traps that produce confidently wrong conclusions and the fix for each. Here is the checklist a senior experimenter carries.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
