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Every result is a comparison to a baseline. The baseline is one variant, treated as the reference, lift, CI, and verdict are all relative to it. By default the Original variant (position 0) is the baseline. That is usually right. Occasionally it is not.

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When to change it

  • You are running Original, A, B, and A is your current champion. Comparing B against Original mixes two changes. Set A as the baseline; the page now compares B to A directly.
  • The Original is a placeholder. Sometimes the Original is synthetic, a control built specifically for the test that no real visitor sees. Set one of the treated variants as baseline.

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How

On the results page, click the Baseline dropdown in the meta bar at the top. Pick a variant. Everything on the page recomputes with that variant as the reference. The URL updates to include ?baseline=<variantKey>. Share the URL and your colleague sees the same view.

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Resetting

Next to the dropdown, a small Reset chip appears once you have overridden the baseline. Click it to return to Original.

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What changes

  • Lift numbers. Every variant’s lift is now vs the new baseline.
  • Verdict copy. “Variant B wins” becomes “Variant B wins vs Variant A”.
  • CIs. The confidence intervals are computed as differences from the new baseline.
  • Charts. The over-time confidence chart plots the new baseline as zero.

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What does not change

  • The data. Every event is still counted the same way.
  • The test itself. No visitors are re-bucketed; the baseline is a display choice only.

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With segments

Baseline override composes with segments, pick a segment first, then change the baseline, or vice versa. Both end up in the URL and share cleanly.