I've seen this working in marketing like magic (Analyzing how paid search would increase revenue by doing a full tracking from lead generation to qualified lead). I basically saw that Twitter and Facebook never generated any final sales and I cut the advertising budget and focused only on specific linkedin and adwords campaigns that would drive leads that would become qualified (I was using pardot + salesforce + unbounce + spreadsheets)
I'm working more with product now as a UX designer and I'm trying to understand how design changes and features would eventually drive growth and focus on the 20% things that bring 80% of the results.
The product that I'm designing is similar to autocad or 3dsmax. It's not simple to do A/B testing like in mobile applications.