Search the Web

Developing a SearchStrategy

What am I searching for?

Before you start to do any searching you must be clear about what you are searching for. Take a moment to ask yourself this question before you start developing a search strategy. What information am I actually looking for? For example, you might be looking for very general information on air pollution, or you might be looking for very specific information on the effects of a particular kind of air pollution produced by a specific industry in a particular part of the world. Thinking for a moment about what you are really looking for will save you lots of wasted time.

Mind mapping

A useful way to develop a search strategy is through using a process known as mind mapping. You'll need a blank sheet of paper on which to produce your mind map. You may want to produce your map using a pencil so that you can change it easily as you go along. Let's work through an example. Imagine you want to find out some information on air pollution. We can describe our search in terms of a simple mind map as follows:

This gives us the basic keywords we want to search for. We have linked them using and to show that we will be combining the two keywords in this way in our search. Doing a simple search now by typing the words air pollution into one of the search engines might find the information we want. This is always worth trying before developing a search strategy in full.

Refining your search strategy

Let's assume that a simple search is not successful. We can use our mind map to refine our search.

First of all we need some more keywords to use with the searchengine

The first thing to do is to think of some alternative keywords for air and pollution.

We can build these into our mind map. In the mind map below atmosphere is an alternative keyword for air. The broken line shows us this is an alternative term. We could use atmosphere or air in a search.

Now let's add some more keywords. Look at the diagram below:

You might notice that Atmosphere and Atmospheric are just different forms of the same keyword. They are alternative terms. Quality is a bit different. It is a broader term. It is about how good the air is in general. Environment is a broader term, which covers the whole area of air pollution. Sulphur dioxide on the other hand is a narrower term. It is a kind of pollution. Broader terms are particularly useful if your search doesn't find enough information. Narrower terms are useful if you search finds too much irrelevant information. It can also be worth thinking of any names of people or organisations that might be associated with the keywords you are searching for. For air pollution we might think of Friends of the Earth or the Department of the Environment. There are no strict rules about how you put your mind map together. The main thing is to get enough keywords down on paper for you to do a good search. To help you produce a good map with lots of keywords, here are some questions to ask yourself as you go along:

Can I think of any alternative words for each of my keywords?
Can I think of any broader keywords?
Can I think of any narrower keywords?
Can I think of any other ways of saying the same thing?

Try and develop a mind map for your own search. If you don't have a search you want to do at the moment, you could try one of the following.You want to find information on Portuguese food.You want to find out if there is any relationship between unemployment and health.

Search statements

Once you have completed your mind map, you will need to turn it into something called a search statement. The search statement is what you will type into the search engine. You could produce one single search statement, but this will usually be too complicated. Also, if it doesn't find the information you want, you will probably not be able to tell why. Just to show you how complicated it might be, here is a single search statement produced from the mind map above. Air pollution or atmospheric pollution or ((air or atmosphere or atmospheric) and (pollution or pollutants or quality or sulphur dioxide)) It is far better to produce a number of mini searches, and try them out one at a time.Here's how to produce your mini searches from the mind map.

Look out for any of the keywords which could be linked together to form phrases which you could search for. For example air pollution, atmospheric pollution, air quality, atmospheric pollutants. Write them all down.
Now look at the different ways you could combine the keywords and phrases using and. For example: air and pollution, air quality and sulphur dioxide, atmosphere and pollutants. Again write them all down.

Try generating some mini search statements from your own mind map.You're now ready to do some searching.

Carrying out the search

Start with your original keywords, perhaps introducing some alternative terms. For example: (Air or atmospheric) and pollution. Have a look at the search results you get back from the search engine. Does it give you enough information? Is there too much irrelevant information? If the search engine has not found you the information you want, you should try some of your other mini search statements. If you find that you are getting too much irrelevant information, you may need to narrow your search. In our example, you might try searching for particular pollutants such as sulphur dioxide. If you find that you are not getting enough information, you may have to broaden your search, using broader keywords. In our example you might try environment. Whenever you find that your search is unsuccessful, try and work out why, so that you can modify your search to get better results. Try searching using your own mini search statements.

Boolean Logic

Boolean logic is a "mathematical logic system" which can be used to improve searching the Internet and World Wide Web (WWW). Boolean logic was invented and named after George Boole, who published his system in a thesis in 1854. It was of little interest to anyone at that time, as it was dealt with pure logic, and was mostly forgotten. However, with the advent of computing and computers, it was realised that although Boolean logic had had little practical use in the 19th Century, it was ideal when applied to searching computerised databases.Boolean logic uses three 'logical operators' to define what a search is to find. These 'operators' are AND, OR, and NOT (also referred to as AND NOT or BUT NOT).

Boolean logic is most easily demonstrated by the use of Venn diagrams. The first operator AND is used to narrow a search. This is unlike it's use in spoken english where it broadens terms when used. For example, if you were searching for pictures of cow and sheep together, then the search "Cows AND Sheep" would result in only pictures of cows and sheep together being found. Pictures of only cows or only sheep would be excluded. The result of this search is shown in the Venn diagram above.

You can use the AND operator with as many terms as you require. We can add another term to our original search which will limit even further the result. The diagram below demonstrates the search "Cows AND Sheep AND Horses ".

As you can see, the result is even smaller that "Cows AND Sheep". Only pictures that contain cows, sheep and horses together will be found. Pictures that contain one or any two of the three animals will not be found.

The use of the operator OR in a search has the effect of broadening a search. The search "Cows OR Sheep" will produce results that contain cows only, sheep only or cows and sheep together. This search result can be seen below.

The final operator NOT eliminates completely one or more terms from the search. The search "Cows NOT Sheep" will obtain results that only have pictures of cows in them. Any pictures that contain sheep, even ones that also have cows in them, will be excluded.

All three operators can be used in as long a search string as is required. However, the more operators used, the more complicated the search becomes. The search "Cows OR Sheep NOT Horses" will produce this following result. All pictures of only cows, only sheep and cows and sheep together will be found. Any picture at all that contains a horse will not be found.

When using Boolean logic to search the Internet and WWW, it may help to try and visualize what you are searching for in the terms of a Venn diagram such as the ones shown above. Try to avoid long complex Boolean searches as it is easy to get confused about exactly what results your search will actually get.Below are some Venn diagrams exercises. If you want you can print out this page and use them to practice mapping out searches using Boolean logic.

Circle the boxes below. One will contain all categories with Cows in them, another all categories with sheep, and the third all categories containing horses.Note how the circles interlink. Now shade the area that represents the results from a search "Cows AND Sheep NOT Horses".This second diagram follows the same idea. First circle all the categories containing each of the four words. Then shade the results obtained from the following search. "Aberdeen OR Edinburgh OR Perth NOT Dundee".