A segment which did not exist prior to their changes, thereby increasing their conversion rate from X to 11X, as there was a 10X increase in conversions post-change.
The segment did exist - users who added a custom theme. Of that segment, they converted 10X more than those who didn't add a custom theme. Ghost then responded by making it easier to add a custom theme, but we aren't told what effect that had on overall conversion.
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A segment which did not exist prior to their changes, thereby increasing their conversion rate from X to 11X, as there was a 10X increase in conversions post-change.
The segment did exist - users who added a custom theme. Of that segment, they converted 10X more than those who didn't add a custom theme. Ghost then responded by making it easier to add a custom theme, but we aren't told what effect that had on overall conversion.