A data-first agency-client relationship is more successful because a data-first mentality encourages 1) iteration, in 2) the places it matters, to create 3) compounding growth.
1) Iteration – Agencies and clients can iterate on successful marketing copy and design to create better results.
2) Places it Matters – Location, location location. By focusing attention on testable areas of the site — areas that will have a high statistical significance and converge on data points quickly — we’re actually testing the areas of the site which will have the most impact. If a page gets 1% of my traffic, why would I optimize it until every other avenue is exhausted? Likewise, if a change is too minor to go through testing, it’s probably too minor to implement in the first place.
3) Compounded growth – A 1% conversion rate win does not stay a 1% win forever. As that win turns into higher revenue, which turns into more analytics and creative, wins compound into big success stories. Losses compound too. Making changes that cause losses can offset hard-won positive results.