Precision
But first, a little searching theory, to see how these techniques can be useful. When you search an online database, you want to find as much relevant information in the database as you can while avoiding getting irrelevant items along with your results.
The "precision" of a search result refers to how much of the information your search retrieved is actually relevant to your needs. Precision is easy to determine: for example, you may have 40 records retrieved by your search, 30 of them are useful, the other 10 irrelevant. If your search retrieves a lot of irrelevant results, you can use some of the techniques below to make a more precise search which will retrieve less irrelevant material. "Recall" refers to how much of the relevant information in the database you were able to find with your search. This is much more difficult to determine: you know you found 30 useful items, but you don't know how much useful information you didn't find. The database may contain another 100 useful items that you did not find, but you wouldn't have any way of knowing that for sure. By using some of the techniques below to increase recall, you can be more confident that you have found at least most of the useful information in the database.
You can increase precision by being very specific and narrow in your search, which will give you few if any irrelevant results, but that risks missing a lot of useful information. You can increase recall by broadening your search and thus finding more useful information, but that will tend to increase the "noise" (irrelevant results you have to sift out) in your results. So, increasing one tends to decrease the other. But you can use the techniques below to find ways to maximize both precision and recall as much as you can. Also, consider the purpose of your search. If you are using an Internet search engine to find a few good web sites on a topic, focus on increasing precision: it doesn't matter if you don't find everything available, and you don't want to have to wade through thousands of irrelevant sites. But if you are using an academic database to do a literature review for an extensive research project, you want to make sure you find as many of the relevant articles as you can, so you would focus on increasing recall even if you have to sort out a lot of irrelevant articles in your results.
The part of a search result that refers to how much of the information was retrieved is actually relevant to your needs is know as:
Test Yourself by answering the following question.
The part of a search result that refers to how much of the information was retrieved is actually relevant to your needs is know as: