You observe that activation into the core product flow fell from 30.0% last week to 26.2% this week after a change to the onboarding experience. You have two traffic segments: self-serve web signups and sales-assisted invites. Last week, self-serve was 70,000 users with 24.0% activation and sales-assisted was 30,000 users with 44.0% activation. This week, self-serve was 90,000 users with 23.0% activation and sales-assisted was 10,000 users with 55.0% activation.
How would you determine whether the overall activation drop is more likely explained by the onboarding change itself or by the shift in traffic mix across segments, and what conclusion do the numbers support?