Why are search results different from suggested similar questions?

Question

Sometimes I will search a topic and skim through dozens of questions on the search results page to conclude that a question hasn't been asked, but when I put the exact search term into the title of a new question, far better results pop up and I find the question has already been answered. Has anyone else experienced this? Why are the similar question suggestions so much better than the search results?

As a simple example related to the recent popular question about Istari, search Why were the Istari forbidden to fight and then compare that to the results if you put it into the title of a new question.

Answer 1

The search bar finds exact results.

It's a very simple algorithm: if you write a list of words into the search bar, you'll get a list of all posts including all of those words, which you can then order by votes or age. Its advantage is that you can also use it for more advanced search, if you know all the different techniques - for example, you can search only within a certain tag, or only for posts within a particular age range, and so on. Perhaps most importantly, you can search answers as well as questions.

Suggested "similar questions" uses a more intelligent algorithm.

I'm not sure exactly what algorithm this is, but clearly it's better at finding similar questions based on inexact matches. See also Detecting similarity between questions : How? on main meta.