June 20 2022

Core Web Vitals and CRUX data.

What is the CRUX data of the Google Core Web Vitals and what is it for? Let's see them together.

We talked a lot about Core Web Vitals and their importance after the Google announcement that made them positioning factors.

Consequently we have implemented a Optimization service Core Web Vitals, in order to improve speed not only on the server side but also at the application level, not very different from what we did before the advent of Core Web Vitals, via the simple Google Pagespeed Insight tool.

However we have increasingly seen situations where for example a mobile score of 60 passed the CRUX test of Core Web Vitals, and scores of 90 that did not pass the CRUX tests.

Pagespeed insight CRUX core web vitals

If we look at the image above for example we find a laboratory test score of 78 (a good value) well below the score of 90 to enter the "green zone", however we see that the evaluation of essential web signals has been brilliantly passed in the Previous 28 days.

What does it mean ? How does it work ?

Core Web Vitals is it about laboratory data or field data?

This is “Field Data”. This means that:

  • Core Web Vitals it concerns real users, in the field;
  • Chrome UX Report (CrUX) is generated from the data collected through Chrome, directly from its users who surf the web;
  • It's all about the performance data of your own traffic, only among Chrome users.

How does Google know how users are experiencing the my site / shop?

Chromium users track their experiences during a page visit. Once a visitor leaves the page, for example by clicking on another page, Google will send the performance and UX metrics to its servers. This is better known as the Chrome User Experience Report (CrUX).

These navigation evaluation data sent by the browser are called beacon in technical jargon.

Chromium beacons are small text files sent by a website to Google that provide information about users' browsing experience. These beacons are used by Google to collect data on the UX of a website and to optimize search results.

Chromium beacons send information about how fast pages load, how often users interact with the site, and whether there are any errors. This information is used by Google to evaluate the user experience of a site and to provide more accurate and relevant search results to users.

Which visitors are excluded from Core Web Vitals?

All Chromium users (today also Microsoft Edge users as it is based on the same engine as Chrome) have their data sent to Google / CrUX. This means that most of the real user experiences of Apple / iOS users may not be sent to Google's servers, as they often use Safari and Linux users may be using FireFox.

Please note that users can disable this setting and prevent the browser from sending their experiences and therefore UX and page speed metrics to Google's servers.

How many visitors do I need to score Core Web Vitals?

Nobody knows. Tests I've conducted in the past have shown that your site needs around 400 page views per month per device (mobile, tablet, desktop), using Chromium to get a summary of the source of Core Web Vitals when using PageSpeed Insights. Keep in mind that this may be the absolute minimum.

When a site doesn't have enough visitors, chances are you need to find other ways to rank higher.

The score is updated every 4 weeks, therefore 28 days, taking into account the 75 percentile of the data in possession.

Although it is possible to monitor the Core Web Vitals For both desktop and mobile devices, only signals will be used for page positioning mobile devices. Also, keep in mind that when it comes to Web Core Vitals scores, the metrics will be rated at the 75th percentile of users. This means that if you wish to satisfy the Core Web Vitals, your pages will need to exceed recommended scores for at least 75% of page visits.

Note: Improving page speed will still have a positive impact on conversion, regardless of the amount of visitors or passing the rating of the Core Web Vitals.

How do I know if I have enough visitors?

When you do a PageSpeed ​​test Insights , you will always see "Lab Data". The “Field Data” will also be displayed, located above the “Lab Data”. When you don't see any colored bar charts, your webpage doesn't (yet) have enough visitors to produce data.

However, if your origin (domain) has had enough visitors to provide a summary, PageSpeed Insights could at least show you a summary of the source. When "Field Data" is not displayed, your website or online store does not have enough visitors and you will not benefit from the ranking factor of Core Web Vitals. Keep in mind, however, that improving page speed, performance, and user experience will still impact conversion and may future-proof you should your visitor numbers increase over time.

Will I still benefit from page speed without enough data / visitors?

Maybe, but not directly. Google won't use lab data if your domain doesn't have enough field data.

It could be said that a site without enough data is still not interesting enough (or cannot be found) for a large chunk of visitors. And because there are some ranking factors, a website already has other ways to get a higher ranking. Of course, good page speed / UX could actually entice people to visit more pages, possibly ending up getting enough data. So, pagespeed in combination with good technical UX still matters, but indirectly in this case. Additionally, a domain or even a specific page needs enough visitors to provide a reliable representation of its top page experience and Web Vitals.

What if one page doesn't have CRUX test data, but others have?

Google Search Console is already grouping pages. Core Web Vitals will do the same. If a page (for example just launched) doesn't have enough visitors, it could go back and reuse data from similar pages. If Google can't find similar pages, it will go back to the source summary.

Currently, you can only see if there is enough data for a specific page and / or a summary of the source. You may need to look into Google Search Console to get an idea of ​​page grouping.

How do I collect data myself when my site does not have enough visitors?

Hopefully, you will have enough traffic to get some data to see the field data within PageSpeed Insights, Google Search Console and CrUX. If not, you can still keep track of your visitors' top Web Vitals and store them wherever you want. For example to Google Analytics or through Google Tag Manager. GoogleChrome has published a library, including code examples on github .

You can also use tools like SpeedCurve, Akamai, and Cloudflare (when you're already using Cloudflare, for example) or cheaper but enriched tools like CWV Insights.

Better to have a high score at the labs or Crux data level?

The correct answer to this question is to state very firmly that LABS data indicate but do not prove.

Many WordPress speed optimization plugins tend only to "fool" these tests with questionable techniques such as delaying all resources and therefore obtaining a very high LABS score perhaps tending to 100. However, very often these scores are over 90 or 100 end up NOT exceeding the CRUX data on-road score.

Google knows it can be wrong and approximate, as well as being deceived, which is why it will always prefer to draw on real visitor data and real browsing sessions to understand the actual speed and performance of your website.

Google Labs are a set of tools and services developed by Google to help webmasters optimize their sites for search engines. One such tool is PageSpeed ​​Insights, which evaluates a site's page loading speed and provides recommendations on how to optimize it. Having a high score in Google Labs can help improve the user experience of browsing a site and get a better position in search results.

CRUX is a data platform developed by Google that uses data collected by Chromium browsers to evaluate the user experience of browsing a website. CRUX analyzes page loading speed, content quality and site ease of use, providing useful information to improve the UX of your site. Having a high score in CRUX can help provide a satisfying browsing experience to users and get a better position in search results.

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