Pages show a recent 'updated' date, or sitemaps report a recent lastmod, but the main content is unchanged or changed only trivially since the previous version. Google's historical data patent describes weighting content changes by significance and says changes to date/time tags may be ignored. Google has not confirmed use of this method, so this is a proxy; cosmetic date changes also mislead readers.
Why does visible updated dates change without substantive content change (historical data patent) matter for AI search?
Google's historical data patent describes weighting content changes by significance and says changes to date/time tags may be ignored. Google has not confirmed use of this method, so this is a proxy; cosmetic date changes also mislead readers.
How do you fix it?
Change the visible date only when the main content materially changes, and say what changed. Tie sitemap lastmod to real content edits, not to template or build timestamps.
How do you find it on your site?
- Crawl the site and extract each page's visible updated date and its sitemap lastmod.
- Select pages whose date changed in the last 90 days.
- Retrieve an earlier version of each from your CMS revision history or the Wayback Machine.
- Diff main content only (excluding navigation, ads and dates) and flag pages where the date moved but the content change is trivial.
Which ranking and citation factors does it touch?
Written for the Historical data patent page (evidence: Patent only). Google has not documented this system in a way a site can test directly, so this check measures a proxy for it, not the system itself.
What is the impact?
Indirect. Estimate only: the main gain is credibility of dates with readers and with systems that rely on them.
What is the evidence?
US7346839B2, Information retrieval based on historical data (Google Patents).
Frequently asked questions about visible updated dates change without substantive content change (historical data patent)
What does "Visible updated dates change without substantive content change (historical data patent)" mean?
Pages show a recent 'updated' date, or sitemaps report a recent lastmod, but the main content is unchanged or changed only trivially since the previous version.
How do you fix visible updated dates change without substantive content change (historical data patent)?
Change the visible date only when the main content materially changes, and say what changed. Tie sitemap lastmod to real content edits, not to template or build timestamps.