Exclude the partial week and split interpretation at the 11 May definition change; pre/post values are not automatically comparable. Calculate each rate from summed orders divided by summed starts, not by averaging row percentages. Add absolute percentage-point change and relative change.
The six complete weeks show a monotonic decline from 4.8% to 3.9%: −0.9 percentage points, or −18.75% relative. The larger step from 4.6% to 4.1% suggests a possible level shift rather than random week-to-week movement, followed by two smaller declines. This is evidence for investigation, not proof that the 1 June mobile release caused it.
Build a line chart with raw weekly rate by Device and overall rate; add a three-week moving average only as a secondary line. Mark 11 May and 1 June as annotations. Compare Mobile and non-Mobile using weighted rates and show weekly denominators. If the decline is concentrated on Mobile after 1 June and definitions are stable within that window, the release becomes a stronger hypothesis. Check missing weeks, denominator drops, delayed order completion, and later revisions before deciding.