Treat those as hypotheses, not findings. At alpha 0.05, testing twenty slices gives roughly a 64 percent chance of at least one false positive even when nothing is real, so two hits is about what pure noise produces. Apply a correction such as Benjamini Hochberg, or better, pre register the segments you care about and confirm any surprise in a fresh test.
Why interviewers ask this
This is a discipline question disguised as a statistics question. Interviewers want to see you resist a tempting result, because slicing until something is significant is how bad launches get justified. Naming the expected number of false positives, distinguishing Bonferroni from false discovery rate control, and proposing a confirmatory rerun all suggest you have been burned by this before.
How to structure your answer
- Quantify how many false positives twenty tests are expected to produce.
- Reframe the two hits as hypotheses rather than results.
- Name a correction and say why FDR control beats Bonferroni here.
- Propose confirming in a fresh test before anyone acts.
Example answer
I would tell them we found two leads, not two results. With twenty independent tests at 0.05, the chance of at least one false positive under a true null is about 64 percent, and the expected count is one. So two is squarely inside what noise produces. Then I would apply Benjamini Hochberg rather than Bonferroni, because Bonferroni across twenty tests is brutally conservative and would probably kill a real effect along with the noise; false discovery rate control is the right tool when you are screening. Usually one or both drop out. If something survives, I still treat it as a hypothesis and say so: the honest next step is a confirmatory test targeting that segment specifically, with the segment declared before we look. I have seen this go the other way, where a team shipped to a segment based on a sliced result and the effect vanished at scale, and the cost was not just the wasted feature, it was that nobody trusted the experiment platform for a quarter afterward.
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See how it worksFollow-up questions to expect
- How does Benjamini Hochberg actually work, step by step?
- When is Bonferroni the right choice despite being conservative?
- How would you design the experiment up front to avoid this situation?
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