Connecting search terms together
In the last section, we identified keywords for our topic by phrasing it as a question: What evidence exists to indicate that body image effects the emergence of eating disorders? The keywords body image and eating disorders were identified. If we were to type just one of these into a database, the results probably wouldn't be quite what we are looking for. We need a way to combine these two keywords to retrieve materials on our specific topic.
Unfortunately, many databases won't let you just type a sentence explaining your topic. You have to pick out the main subjects or key words and connect them together using what we call "Boolean operators".
There are three frequently-used Boolean connectors with which you should be familiar: And, Or, and Not. Let's discuss what each one does and why you would use it.
The connector AND
The and connector tells the computer that we want to retrieve items which contain all the words and phrases we link together.
If we type the phrase body image and eating disorders into the database, the computer will look for all the records which contain the phrase "eating disorders" and also the phrase "body image". If an article just contains one of the terms but not the other, it won't be included in your results. The search can be diagramed like this:
Note that the list of items which will be retrieved is represented by the shaded area which contains both phrases.
If we type the phrase body image and eating disorders and adolescents, the computer would look for each of the three concepts in the same article. The search would be diagramed like this:
Note that the more words/phrases that you connect with and, the smaller the shaded area of items which contain all the words. So, and is used to narrow your search and will retrieve fewer items.
There may be times when you want to increase your results, that is, to find more articles. The next page discusses a Boolean operator which does just that.
There are times when a single subject heading or key word isn't specific enough to express the topic you wish to find. At these times, you need to search for a combination of words or phrases. Continue with the next section to learn more about combining search terms.
The connector OR
The or connector tells the computer to look for any of the words or phrases. Or can be used to look for related or synonymous terms. For example, anorexia is a type of eating disorder. If you wanted to retrieve a list of records which contain either anorexia or eating disorders, you would type the phrase, anorexia or eating disorders. It would be diagramed like this:
Notice that the shaded area covers both circles because if the record contains either the word "anorexia" or the phrase "eating disorders", it will be retrieved. Connecting your search terms with or will broaden it and will retrieve more items. (Remember, you get "more with or".)
The and and or connectors tell the computer which subjects or key words we want to include. On the next page, we will learn about an operator which tells the computer to exclude a term.
The connector NOT
The connector not is used to exclude irrelevant terms from your search results. For example, you have already done a search on eating disorders and you've noticed that most of the articles mention anorexia. You wonder, what are the other types of eating disorders?
Typing the search phrase, eating disorders not anorexia will retrieve items which contain the phrase "eating disorders" and then exclude any record which contains the word "anorexia." It would be diagramed like this:
The shaded portion of the "eating disorders" circle which represents your results is now much smaller because you have excluded the term "anorexia." Thus not is used to narrow a search and will retrieve less items.
Be careful using the connector not. You can sometimes take out items which might have been useful to you. For example, assume there is an article in the database you're searching with the title The other eating disorders besides anorexia. This article lists every other type of eating disorder and would be perfect for your needs. However, because you added not anorexia to your search, you excluded it from your results.
The and and or connectors are the most commonly used operators. They can be used individually or in combination with each other. The next page contains some examples.
Using more than one connector
Now that you know how the different Boolean connectors work, you can use them to link any number of terms together. Remember that and and not both make your search smaller. Each time you link a term using either of these connectors, your results get smaller. If you use them too many times, you may end up with zero results!
Linking search terms while using more than one connector often requires that you use parentheses ( ) which tell the computer which terms you want to search first.
Let's say you want to find articles about either eating disorders or anorexia and you want the articles to also be about body image. To make sure the computer is not confused, you should type your search like this: (eating disorders or anorexia) and body image.
The parentheses tell the computer to first search for all the articles which contain either "eating disorders" or "anorexia" and then retrieve only those articles from the first set which also contain "body image."
Here's the diagram for the search, (eating disorders or anorexia) and body image, without the shading. Which area of this diagram would be shaded?
In the next section, we'll discuss ways to search for multiple word endings, for example the terms eat, eats, eating, etc.