GPT for Video Tag Test v1
We (the Chrome Speed Metrics Team) recently outlined our initial research into options for making the CLS metric more fair to pages that are open for a long time. We’ve received a lot of very helpful feedback and after completing the large-scale analysis, we’ve finalized the change we plan to make to the metric: maximum session window with 1 second gap, capped at 5 seconds.
Read on for the details!
How did we evaluate the options? #
We reviewed all the feedback received from the developer community and took it into account.
We also implemented the top options in Chrome and did a large-scale analysis of the metrics over millions of web pages. We checked what types of sites each option improved, and how the options compared, especially looking into the sites which were scored differently by different options. Overall, we found that:
All the options reduced the correlation between time spent on page and layout shift score.
None of the options resulted in a worse score for any page. So there is no need to be concerned that this change will worsen the scores for your site.
Decision points
Why a session window?
In our earlier post, we covered a few different windowing strategies for grouping together layout shifts while ensuring the score doesn’t grow unbounded. The feedback we received from developers overwhelmingly favored the session window strategy because it groups the layout shifts together most intuitively.
To review session windows, here’s an example:
We also implemented the top options in Chrome and did a large-scale analysis of the metrics over millions of web pages. We checked what types of sites each option improved, and how the options compared, especially looking into the sites which were scored differently by different options. Overall, we found that:
All the options reduced the correlation between time spent on page and layout shift score.
None of the options resulted in a worse score for any page. So there is no need to be concerned that this change will worsen the scores for your site.
Decision points
Why a session window?
In our earlier post, we covered a few different windowing strategies for grouping together layout shifts while ensuring the score doesn’t grow unbounded. The feedback we received from developers overwhelmingly favored the session window strategy because it groups the layout shifts together most intuitively.
To review session windows, here’s an example:
Read More at GPT for Video Tag Test v1
