Hi,
First of all: I think apart from QDF results, effects of this are rather small and trumped by such things as the actual content and value a page offered. Nevertheless I got to wondering how the publication date and modification date are used ... effectively and correctly.
Fact: Google displays the publication date on SERPS (if it is given via schema or through the CMS or in any other form). This also applies if you have a date of last modification, for example via schema.org/dateModified - regardless of the extent of changes.
Google only considers the publication date. Google also uses it as an indicator for "freshness". There are quite a few articles on that out there, ex: http://www.kevinmuldoon.com/change-date-article-boost-seo/ and http://www.viperchill.com/new-seo/
Q1: In my opinion, faking the publication date is at the very least a darkish grey area which nonetheless seems to still work. Would you agree?
Q2: Would you see it as legitimate to (at some point after thoroughly reworking one page) update the publication date to the date of republication?
Case in point: I have a page with book reviews. These reviews do not really go stale - much like recipes; tastes may change a bit, but essentially it stays the same. I find it somewhat irking to see a 10 year old date there - even if I maybe have restructured and rewritten, maybe even completely redone a review...
But apart from the question of whether to ever "update" your publication date. I started pondering when it was proper to change the modification date (especially as it seems to have little effect apart from serving as date for last changes in headers, caches etc.)?
For example, content changes when
- Manually changing text
- a visitor leaves a comment
- a visitor gives a book/article/page a rating
- a visitor gives a book a rating and this rating is part of another entity's aggregate rating
Q: Which of these events would warrant an update of the last modification? ratings and aggregate ratings typically only change single numbers (vote count and sums/averages); yet there is [legitimate] change and it is utilised in SERPS (review stars).
I am still hesitant.
My answers would be: Changing the publication date might be valid in case of a MAJOR overhaul with new or lots of extra content - when, for example you could publish the same article again in another issue of the same print magazine the article has been published in before; and all of those changes warrant an update of the last modification, at least as it is currently used, i.e. only to show when change has happened with any real influence.
Personally I'd wish for lastModified carrying more weight compared to pubDate AND especially for more google-side checks if actual change has happened. (To be ignored in case of small things like legitimately switching a sentence or correcting a typo; to be penalised if changed when nothing really changes; to honour when real change happens)
Looking forward on your opinions for dating content - and of course on your hints what I am forgetting.
Nico