"The other thing to keep in mind when looking at how Google works today today versus some years ago, is that Google is moving further and further away from keyword matching (along with PageRank via links) as most important for ranking results and MUCH more towards machine intelligence. Google tries (and is generally succeeding) at figuring out what one"really" wants, based on who you are, where you live, search history etc. (personalization) and what others "like you" doing related/similar/same searches "determined" (based on click and other signal history) to surface pages that are "most likely" to be valuable to you and answer your question. What this means is that you may now not even find your keywords or phrases (unless you put them in quotation marks--...perhaps...) in your results if Google has determined that it is more likely that certain pages that do not even INCLUDE your keywords are more likely to be relevant than some that do."
University of Rochester
Outreach Business Librarian
"Google’s progression has been from search engine to marketing machine, and that’s still the trajectory they’re on. I’ve used Duck Duck Go for years now, especially when I need to find legitimate information rather than opportunities to purchase whatever I’m researching. I haven’t noticed a big change lately, but that doesn’t mean there wasn’t one.
I’m not surprised you didn’t find much on their site; we’re not their target demographic, and they guard their algorithms like a dragon sitting on a hoard.
Duck Duck Go searches against Google’s index, but uses their own algorithm. I recommend them to any serious researcher."
Karen Bleier, Collection Management & Resource Sharing Librarian, Park University, Missouri