Webmaster Trends Analyst John Mueller answered questions about Core Web Vitals and how the scores are calculated. He also discussed the possibility of noindexed pages being be used as part of the Core Web Vitals calculation in the new ranking signal that is coming soon.

Core Web Vitals

The Core Web Vitals are user experience metrics. They are a group of metrics that Google chose to represent how well a web page downloads and presents a good user experience for site visitors.

There are three Core Web Vitals metrics:

1. Largest Contentful Paint (LCP)
   How fast a web page is perceived to load
2. First Input Delay (FID)
   How soon a visitor can interact with a web page
3. Cumulative Layout Shift (CLS)
   How stable web page elements (like buttons, text and images) are while the page is downloading, without shifting about.

Those three metrics are scheduled to become ranking factors sometime in 2021. That is why many publishers and SEOs are concerned about how Google calculates the core web vitals score because, as a ranking factor, there is a possibility that it may impact rankings in certain scenarios.

Screenshot of Google’s John Mueller Discussing Noindexed Pages and Core Web Vitals

Screenshot of Google’s John Mueller discussing why noindexed pages might be used to calculate Core Web Vitals score

Lab Data and Field Data

Knowing what lab data and field data are is key to understanding John Mueller’s answer.

Lab data, in reference to web vitals scores is an estimate of the score. The lab data scores are generated in a simulated environment.

The goal with lab data is to give a publisher an idea of what could be problematic.

Field Data is a score based on actual site visitors under real-world conditions.

It’s the field data that Google will be using to calculate the associated ranking signal score.

Publishers concerned about their ability to rank are concerned with how field data is calculated.

• Does Google use actual page score?
• Does Google use an average of several pages to calculate the core web vitals score?

Noindex and Core Web Vitals

Noindex is a signal that a publisher can use to tell Google not to include a web page in Google’s search results.

According to Google’s official documentation:

“You can prevent a page from appearing in Google Search by including a noindex meta tag in the page’s HTML code, or by returning a noindex header in the HTTP request.

When Googlebot next crawls that page and sees the tag or header, Googlebot will drop that page entirely from Google Search results, regardless of whether other sites link to it.”

The question asked of Google’s John Mueller was whether a noindexed page will be used to calculate the web vitals score.

What made this question important was that the publisher was blocking these pages because they were very slow and the publisher did not want those pages used as part of the calculation of the core web vitals score.

This is the first question:

“With regards to core web vitals, field data is going to be the one to pay attention to, correct (in terms of ranking signals)?”

John Mueller’s response:

“Yes, yes, it’s the field data.”

Google May Aggregate Pages for Core Web Vitals

In the follow up question Mueller reveals how Google may in some cases calculate the core web vitals score as an average of multiple pages.

This is the question:

“When this becomes a ranking signal… is it going to be page level or domain level?”

Mueller answered:

“…What happens with the field data is we don’t have data points for every page.

So we, for the most part, we need to have kind of groupings of individual pages.

And depending on the amount of data that we have, that can be a grouping of the whole website (kind of the domain).

…I think in the Chrome User Experience Report they use the origin which would be the subdomain and the protocol there.

So that would be kind of the overarching kind of grouping.

And if we have more data for individual parts of a website then we’ll try to use that.

And I believe that’s something you also see in search console where we’ll show like one URL and say… there’s so many other pages that are associated with that. And that’s kind of the grouping that we would use there.”

Mueller is clear that the core web vitals score may not always be calculated on a page by page basis.

Will Slow Pages Affect Overall CWV Score?

The person asking the follow up question then related that they have a set of pages that are slow and are no-indexed and asked if those pages can impact the core web vitals score.

“We gave this set of pages that they are slow. And these we have a noindex on them… they are very slow. And that’s why we don’t want it to be accounted for.”

Mueller responded:

“I don’t know for sure how we would do things with a noindex there. But it’s not something you can easily determine ahead of time.

Like, will we see this as one website or will we see it as different groupings there.

Sometimes with the Chrome User Experience Report data you can see like, Does Google have data points for those noindex pages? Does Google have data points for the other pages there?

And then you can kind of figure out like okay, it can recognize that there is separate kinds of pages and can treat them individually.

And if that’s the case, then I don’t see a problem with that.

If it’s a smaller website where we just don’t have a lot of signals for the website then those noindex pages could be playing a role there as well.

So I’m not 100% sure but my understanding is that in the Chrome User Experience Report data we do include all kinds of pages that users access.

So there’s no specific kind of, will this page be indexed like this or not check that happens there because the indexability is sometimes quite complex with regards to canonicals and all of that.

So it’s not trivial to determine… on the Chrome side if this page will be indexed or not.

It might be the case that if a page has a clear noindex then even in Chrome we would be able to recognize that. But I’m not 100% sure if we actually do that.

I would also check the Chrome User Experience Report data. I think you can download data into BigQuery and you can play with that a little bit and figure out how is that happening for other sites, for similar sites that kind of fall in the same category as the site that you’re working on.”

Pages that Users Access

While Mueller hedged by saying that he wasn’t 100% certain if Google used noindexed pages, he did affirm that the Chrome User Experience Report included all kinds of pages (which in this context presumably includes noindexed pages).

The reason they are included is because, according to Mueller:

“…we do include all kinds of pages that users access.”

The logic behind using noindexed pages can be that because users can access a page then it is going to be measured. The reason is because a user will experience the noindexed pages, regardless if those web pages are blocked to Google.

Though Mueller wasn’t 100% certain, until there is further clarification, it may be prudent to assume that noindexed pages will be measured as part of the core web vitals ranking score.

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