The closer we get to May the more hype there is around Google's new ranking factor. During a Google Office Hangout, John Mueller answered the question of whether scoring Core Web Vitals will include sites whose users come from countries with predominantly free Internet. We will get to that in a moment, but in the meantime let us look at the data we get during the tests.

Laboratory data / Actual data

It's worth being aware of what one is and what the other is, especially since the results don't necessarily go hand in hand, and it's the actual (field) data that search engine algorithms will take into account.

Testing Core Web Vitals with Lighthouse produces what we call lab data. Lab data is estimated result obtained in simulated environment.

In contrast, field data, which is what is reported in PageSpeed Insights, is based on actual data. Actual data is collected from real users of the site who have anonymously provided information about the site's download speed.


The person asking the question during the Google Office Hangout noted that she had optimized her site and had achieved a maximum score of 100 in the lab tests. But when the field data was updated, she saw that her scores (based on actual site visitors) reported in Google Search Console actually dropped and were significantly lower than the simulations predicted by Lighthouse.

The crux of the question was why the simulated lab data reflects changes made to improve Core Web Vitals score, but Google Search Console shows that the metric is deteriorating.

Mueller began his response by reminding the questioner that there was a delay in reporting field data. This, however, the questioner knew about and added that she had waited more than 28 days to see the updated results and the results were worse.

Mueller replied that it was difficult to talk about this particular case without looking at the details and at this point the discussion became very interesting.


"One of the things I would try to do is try to figure out which part of Core Web Vitals the problem is, whether it's Largest Contentful Pain or maybe CLS, and based on that I would try to figure out where it might be coming from."

He then slightly downgraded the value of laboratory tests by saying:

"One of the things that tends to happen with lab data versus field data is that lab data is basically an assumption. It is just an approximation of what our systems think might happen in a real-world environment. Because there are a lot of variables that affect the results, like where users come from, what equipment they use and so on, you can use the lab data to improve the results, but you don't necessarily see a clear relationship between it and the actual results."

What about countries with poor internet

As we know, internet access is not the same everywhere, so the next question was whether slower speeds are taken into account in different countries. The questioner wanted to know if there were differences in results for countries with slow mobile connections.

He went on to note that this could put his site at a disadvantage in countries where users from developed countries with faster internet connections predominate.

The basis of this question is that Core Web Vitals is measured using real user data, not lab data. If a user is using a low quality mobile phone with a low quality data connection, Core Web Vitals scores will be lower than someone from another country who has a faster internet connection and a high end mobile phone.

Mueller replied:

"I don't know what the final configuration will be. We have country information in the Chrome User Experience Report data. With that, we'll be able to determine where users are mainly coming from. But the general idea is that users should have a good experience. And if most users don't have them, for whatever reason, then that's essentially what will apply. At least as far as I know, that's the general point of view. If 90% of your users are coming from places that are free, and 90% of them have not had the best experience with your site, that will be taken into account."

John Mueller has made it clear that there will be no concessionary tariffs for sites whose users come from countries where the Internet connection is slower. Companies whose users come mainly from countries with fast Internet are not necessarily competing with sites whose user base comes mainly from countries with slower Internet.


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