TIP of the day: order of basic search results

When you are running a search, do you consider the sequence in which you want your results displayed? Sometimes doing so can make it much easier to find the results you want.

By count

By count is the default sequence - the resources are listed in order of the number of results they have on the search terms. Within the same number of results they are sorted into alphabetic order by title.

By resource

By resource is a simple alphabetical order on resource title.

Ranked

Ranked is radically different. The results are present at the article level rather than the resource level. The articles most likely to be relevant to you are at the top. "Most likely to be relevant" is determined by the density of the search results based on the assumption that if an article is about a particular topic, that topic will be mentioned more frequently than in an article that only casually touches on the topic.

Search ranking is a complicated process; we started with "standard" algorithms, but may have some subtle tweaks, and plan more in the future. (Like Google -- it's always changing.)

In simple terms, it's a measure of how similar the target "document" (an article in a book, in our case) is to the query. Now there's a big difference in document length and query length, but the basic idea is that you rank higher documents in which rarer query terms appear in higher frequencies. 

So if I search for 

the huge dog

you'll get a higher rank for documents in which "huge" and "dog" appear frequently, but the frequent appearance of "the" in a document won't promote its rank much, because "the" is not at all rare. 

If you want to go further, start with reading about "tf-idf" http://en.wikipedia.org/wiki/Tf–idf

Beyond that, every search engine starts introducing special hacks and tricks to improve ranking, by usually subjective criterica. (Search "pizza san jose" while you're in San Jose, California, and Google gives higher rank to pizza restaurants near year. Search for the same thing while in Costa Rica, and it'll promote San Jose, Costa Rica restaurants higher in the list, etc.)