Computers are basically giant calculators. Databases and search engines can't think of words the same way we do - as signs representing meanings. They have to think of a word as a thing that can be used in sums.
An illustration I like using is to think about a deck of cards. You can tell the computer to find all of the black cards and it will. You can tell it to find all of the hearts, and it will. You can tell it to find all of the Jacks, and it will - but you can't tell it to find a royal flush, because then it has to think about how the cards relate to each other. Unless you tell the computer exactly what cards are in a royal flush, then it won't be able to find one for you.
This is where Boolean Operators come in. They act as commands telling the computer how the words relate to each other and what should be done about them.
The most common Boolean terms are AND, OR and NOT.
AND tells the database to look specifically for documents that have both of the terms you are searching for. For example, if you ran a search for "rotator cuff", you might get several hundred results. If you ran a search for "injury", you might get several thousand. Most of those articles would be completely useless for an assignment about rotator cuff injuries. However, if you searched for "rotator cuff" AND "injury", the database would only return search results with both terms. It would not find any articles about rotator cuffs that did not include the word "injury", nor would it return any articles about injuries that did not mention "rotator cuff". This could cut the results down from thousands to only a hundred or so. Any other terms you added with an AND would cut the number of results even further.
But what if there was a brilliant journal article that consistently used the word "shoulder" instead of "rotator cuff"? The search above wouldn't find it, because it was missing one of the essential search terms.
This is where OR comes in.
You use OR to tell the database or search engine that these words are interchangeable, and you and happy to accept any article with either (or both). So, ("rotator cuff" OR "shoulder") AND "injury" should pick up any articles that use "shoulder" instead of "rotator cuff", and make sure the word "injury" is included. The brackets in this case are just like the brackets in a mathematical problem - they help the computer to know which 'sums' to do first in the 'equation'.
OR can also help with controlling your search. Say you particularly wanted to know about rotator cuff injuries in sports that involve over-arm bowling. The most obvious ones are cricket and baseball, so you could run a search that looked like this: ("rotator cuff" OR "shoulder") AND ("cricket" OR "baseball") AND "injury".
You will probably find the thousands of results you had to start with have now been whittled down to twenty or so.
Now, if you found you were constantly getting articles about lacrosse, and you wanted to get rid of them from your search results, you would think about using NOT.
NOT basically tells the database or search engine to shut out any articles containing those terms. So, adding NOT "lacrosse" to your search would get rid of any articles containing the word "lacrosse".
Of course, there might be a really good article that uses the word "lacrosse" in one sentence, and the database will reject it just like all of the other lacrosse related articles. You should think carefully about using NOT in your searches. It can be very useful for getting rid of 'noise', but it can have it's downside.
There are other Boolean Operators that you can use in different databases and search engines, but these three are standard for almost all of them. You should check the database guides for the particular database you want to use to see what other operators it offers you.
Showing posts with label search strategy. Show all posts
Showing posts with label search strategy. Show all posts
Thursday, September 25, 2008
Tuesday, August 26, 2008
Constructing a Search Strategy #1 - Key Terms
If you want to find good information for your assignments, you'll need a good plan of attack.
Your "search strategy" is the plan of attack you come up with before you even try to use a catalogue or a database. As you undertake your search, your strategy will evolve and change, but you need to have an idea of what you are going to look for and how you are going to look for it before you even start.
The first step is to sit down with your assignment and take a good look at the question you want to answer. Pull out all of the key terms and write them down on a blank sheet of paper.
The key words are the nouns and verbs, and any adjectives or adverbs that are necessarily linked to those nouns and verbs.
For example, in the sentence "Find three treatments for rotator-cuff injuries and discuss their relative merits, using systematic reviews and clinical trials to illustrate your conclusions" the following key terms can be found:
From there, highlight the words that are telling you to do something (the "action terms") in one colour and ignore them for the time being. If we take the above example:
The exact number of treatments you need to find could be considered part of the instructions, so you could make that first point "Find three".
This leaves you with a number of key terms that can be used to form your search strategy:
Now you need to sit down with a fresh piece of paper and brain storm those key terms. What other words can you think of that are related to those terms? Are there any synonyms that might be used instead? Any antonyms which might be relevant?
Think about how the terms relate to each other. Which terms should you search for together, and which should be broken up for the search? For example, "Rotator-cuff injuries" should probably be split up, as both "rotator-cuff" and "injuries" have a number of synonyms and it would be easier to use them if the two terms weren't always linked.
Are there any terms which might make the search more difficult and should be kept out for the time being (in this example, "Relative merits" describes the kind of information you are looking for, rather than something you need to find information about). It also describes something you should be doing with this information (comparing the merits), so perhaps this term should be moved to your list of "action" words.
Now you should have a list of terms that you can use to look for information. How you use those terms depends on what search tools you are using. Is it a library catalogue? A journals database? An Internet search engine?
We'll look at each of these in future posts.
Before we leave this topic, though, I should point out that the "action terms" (the ones we are ignoring for the search) are still very important, and you should keep that list of them somewhere safe. When you have finished finding the information you need, those "action terms" will tell you what you need to do with it in order to pass the assignment. Definitely worth paying attention to.
Your "search strategy" is the plan of attack you come up with before you even try to use a catalogue or a database. As you undertake your search, your strategy will evolve and change, but you need to have an idea of what you are going to look for and how you are going to look for it before you even start.
The first step is to sit down with your assignment and take a good look at the question you want to answer. Pull out all of the key terms and write them down on a blank sheet of paper.
The key words are the nouns and verbs, and any adjectives or adverbs that are necessarily linked to those nouns and verbs.
For example, in the sentence "Find three treatments for rotator-cuff injuries and discuss their relative merits, using systematic reviews and clinical trials to illustrate your conclusions" the following key terms can be found:
- Find
- Three treatments
- Rotator-cuff injuries
- Discuss
- Relative merits
- Systematic reviews
- Clinical trials
- Illustrate
- Conclusions
From there, highlight the words that are telling you to do something (the "action terms") in one colour and ignore them for the time being. If we take the above example:
- Find
- Discuss
- Illustrate
- Conclusions
The exact number of treatments you need to find could be considered part of the instructions, so you could make that first point "Find three".
This leaves you with a number of key terms that can be used to form your search strategy:
- Treatments
- Rotator-cuff injuries
- Relative merits
- Systematic reviews
- Clinical trials
Now you need to sit down with a fresh piece of paper and brain storm those key terms. What other words can you think of that are related to those terms? Are there any synonyms that might be used instead? Any antonyms which might be relevant?
Think about how the terms relate to each other. Which terms should you search for together, and which should be broken up for the search? For example, "Rotator-cuff injuries" should probably be split up, as both "rotator-cuff" and "injuries" have a number of synonyms and it would be easier to use them if the two terms weren't always linked.
Are there any terms which might make the search more difficult and should be kept out for the time being (in this example, "Relative merits" describes the kind of information you are looking for, rather than something you need to find information about). It also describes something you should be doing with this information (comparing the merits), so perhaps this term should be moved to your list of "action" words.
Now you should have a list of terms that you can use to look for information. How you use those terms depends on what search tools you are using. Is it a library catalogue? A journals database? An Internet search engine?
We'll look at each of these in future posts.
Before we leave this topic, though, I should point out that the "action terms" (the ones we are ignoring for the search) are still very important, and you should keep that list of them somewhere safe. When you have finished finding the information you need, those "action terms" will tell you what you need to do with it in order to pass the assignment. Definitely worth paying attention to.
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