Ask If two subject lines show a 3–5% open rate difference, how do you tell if it’s really the wording?

[Dean101]

You start by checking sample size and statistical significance, because small lists can swing randomly. Then you look at whether the audience segments were truly identical or if one group had different behavior patterns. Running the test multiple times or rotating variants helps confirm consistency. You can also break down results by device or geography to spot hidden biases. If the gap persists across repeated, controlled tests, then wording is likely the real driver of the difference in engagement.