The science behind Google Web Vitals metrics

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Last month we reported on the Web Vitals project, with which Google means to give websites a precise reference to measure the key quality signals to ensure a good user experience. In recent days, Google has then announced that the set of metrics related to page experience will become a ranking factor in 2021, and in the meantime we can find out a little more about the reasoning that led the action of the Mountain View team and gather information about the science and studies behind the Web Vitals.

Google’s explanations on Web Vitals

The focus on this project comes from an article published on the Chromium blog and signed by three authors – Amar Sagoo, Staff Interaction Designer; Annie Sullivan, Software Engineer; Vivek Sekhar, Product Manager – who enter into the details of the initiative, designed as said to help business owners, marketing experts and developers identify opportunities to improve the user experience.

The signals derive from an extensive work by numerous researchers in the areas of human-computer interaction (HCI) and user experience (UX), but identifying the right metrics and thresholds is not as simple “as taking a research paper and find the answer”.

The user journey – and its slow downs

The googlers then begin to explain the approach used for this work, using a similitude:

Imagine you’re walking through an unfamiliar city to get to an important appointment. You walk through various streets and city centers on your way. But here and there, loose paving stones make you trip, there are slow automatic doors you have to wait for to open, and unexpected construction detours lead you astray

All of these events interrupt your progress, increase stress and distract you from reaching your destination.

Even the people who use the web are on a journey – as we said also talking about the search journey – and each of their actions is a step in what would ideally be a continuous flow. Just as in the real world, they write, ” they can be interrupted by delays, distracted from their tasks and led to make errors.”, and in turn these events can lead to a reduction in satisfaction and the abandonment of a site or the entire journey.

Which are the interruptions of the user journey

The removal of interruptions and obstacles is therefore the key to achieve a smooth journey and having a satisfied user.

The delay in loading pages

The most common type of interruption in the Web user experience is waiting for page loading.

For a developer, page loading is a discreet event and some delays may seem inevitable.

However, page loading in most cases happens in the middle of a user’s journey, while he reads the latest news facts, searches for a new product or adds items to an online shopping cart.

So, from the user’s point of view stopping to load a certain page does not represent a natural pause: he has not yet