No, not if you do an A/B split test because it provides you a clean control that fluctuates with the site and seasonality. If you do not have a clean control group, you can detrend the data by dividing the % lift of the schema affected pages by the lift of the direct channel. If that number is over 1, then the structured data is correlating with improved results. The distance or % above 1 is the detrended net lift.