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The Customer Experience Index (CEXi) Helps Online Businesses Benchmark Web Performance and User Experience


The CEXi is a compound index that quantifies the desktop and mobile user experience of a web application far more accurately than any single metric. The CEXi combines objective, measurable aspects of performance, such as page load speed from both mobile and desktop simulations, with specific weighting calculations to provide online businesses with an overall performance score that simulates the actual feeling, positive or negative, of using their web applications for a modern, cross-device user.

The Customer Experience Index focuses on three aspects of web performance: speed, parity of experience (across devices), and how well a site is optimized in relation to its complexity.

  • Speed – For the CEXi, key performance metrics, such as Time to Start Render (TTSR) and Time to Display (TTD), are collected and blended, and then weighted 50/50, for both mobile and desktop users. The mobile user simulation uses a 3G connection and an iPhone 5 with Safari browser, while the desktop user simulation uses a standard broadband connection and the latest version of Chrome. Then Yottaa takes the two resulting figures and weights them 60/40 – 60 percent mobile, 40 percent desktop, to match the current trends in web device usage in the U.S.
  • Device Parity – The CEXi compares the complexity of a desktop site for an online business versus its corresponding mobile site. Ideally, a site should be built on mobile-first principles, leading to a design that is equivalent for all users in functionality, and also performs well for all users.
  • Performance Power – While an eCommerce site should not be penalized for choosing to create a simple site, there are some sites that go above and beyond the call of duty by providing a super-rich experience that is also remarkably fast. To reward these companies, Yottaa developed a “bonus” score that bumps up the existing score by 25-50%, depending on how much power it packs from an optimization perspective. This is done by comparing the page weight and Time to Start Render for mobile (the more difficult of the two platforms to optimize). Conversely, Yottaa gives an equivalent penalty to those sites that should be fast, because they’re relatively lightweight, but are not.
To get your organization's CEXi calculated and see where you stand in comparison to other companies, please complete the form on the right.