Once you have developed a research question that has multiple concepts, you're ready develop a search strategy so you can carry out effective searches in computer databases that will find the best information for your topic. Let's continue with the research question, "What is the effect of illegal immigration on the U.S. economy?"

Dividing a Research Question into Concepts

The first step in the process of developing a search strategy for a topic is to analyze the research question (or research topic) and break it down into main ideas or concepts such as "illegal immigration" and "U.S." and "economy" in the previous example. A typical research question should be able to be divided into two or three (or occasionally four) concepts. If you can only identify one concept, the topic is probably too general. More than three or four concepts is likely to be too specific.

Breaking a research question (or research topic) into appropriate concepts can sometimes be a tricky process. A topic can often be divided into various different combinations of concepts. Each concept should be stated as precisely and succinctly as possible and words that describe the relationship between concepts should not be included. Only the most significant words from the research question (or topic statement) are usually included as terms for one of the concepts. Words that are not essential in defining a concept (such as "what" and "effect" in our example) should not be included as terms.

Finding Synonymous or Related Terms for Each Concept

Once the topic has been broken into basic concepts, as many search terms as possible should be listed for each concept. Any terms that are synonymous or closely related to a concept should be included. Remember that certain controlled vocabulary terms, such as terms that include subheadings and inverted headings, should be rewritten slightly to be used as keyword terms. Subheadings should usually be sepaxrated from the main heading and are commonly included in separate concepts. For example, the subject heading "immigration--economic effects" should be divided, putting the term "immigration" in one concept and the terms "economic effects" in a separate concept. Words in inverted headings should be searched in both the original and reversed form.

If we take the concept, "illegal immigration", from our search example, we might list the following additional related terms for that concept: "illegal immigrants", "illegal aliens" or "undocumented workers". For the concept, "economy", we could also list "economics" ". For the concept, "U.S.", "United States" and "American" should also probably be included.

Using a Search Worksheet

It is very useful to organize the various search terms for each concept in a research question by using a "Search Worksheet" as is shown below.

Research Question (or Topic):

What is the effect of illegal immigration on the U.S. economy?

CONCEPT #

Search Terms

1	illegal immigration	illegal aliens	undocumented workers	x	x
2	economy	economics	x	x	x
3	U.S.	United States	American	x	x

Boolean Logic

Most electronic databases allow users to create various relationships between search terms which can define a topic very precisely. These relationships are created by inserting special words, referred to as "logical operators", between the search terms. There are two logical operators most commonly used by most electronic databases. The operators are: OR and AND. The use of these operators is called Boolean Logic (named after George Boole, a 19th-century British mathematician.)

The OR operator is used between terms with the same or similar meaning--between different terms for the same concept. Placing an OR between two search terms instructs the computer to search for all of the records containing either the first term OR the second term. In this way the OR operator expands a search. It is common to use "OR" between each of the terms related to one concept. For example, if you type: "illegal immigration OR illegal aliens OR undocumented workers", the computer would retrieve all the records that are related to any of those terms--either "illegal immigration" or "illegal aliens" or "undocumented workers".

The AND operator is used between different concepts. Placing an AND between two terms instructs the computer to search for all of the the records containing both the first AND the second term. The AND operator narrows a search. "AND" is typically used between different concepts. For example, if you type: "illegal immigration AND economy," the computer would search for all the records dealing with both "illegal immigration" and "economy."

The goal of a search strategy is to be able to do a series of related searches that result in a "set" of all of the records specifically related to your topic with few, if any, records that are not relevant to the topic. A "set" is the group of records that results from any search. The number of records retrieved by a search are often referred to as "hits". Records retrieved by a search that are not relevant to the topic are sometimes called "false hits".

Carrying Out a Search Strategy

Let's carry out the search strategy we've developed by completing a series of searches on the InfoTrac Searchbank Academic ASAP database. Follow the steps as we describe them below. To do Boolean searches and create and combine search sets in InfoTrac Searchbank databases, you have to use the "PowerTrac" mode.

Connect to InfoTrac Searchbank, choose Academic ASAP and select the "PowerTrac" mode, as follows:

1. On the World Wide Web, link to http://www.searchbank.com/searchbank/plan_main and enter your Library Card Number from your PLAN library card (Peninsula Library System) in the entry box. (Be sure to click in the box before you type your number.)

2. Select Academic ASAP from the Database List by clicking on the blue underlined words: "Academic ASAP".

3. At the next screen, click on the "PowerTrac" button (near the bottom of the screen) to switch to the "PowerTrac" advanced search mode.

Once you're in the PowerTrac mode, the first step is to search for all terms for each concept, one concept at a time. Follow your Search Worksheet closely as you carry out a search in any computerized database. The purpose of identifying an extensive list of terms for each concept is to be able to find all the records in the selected database(s) that have any information related to that concept. To expand a search to find the most articles related to a concept, use the OR logical operator between each of the terms related to the concept.

4. Click in the entry box, type in the search terms for our first concept, with OR between each term:
illegal immigration OR illegal aliens OR undocumented workers
and then press Enter or click the "Search" button.

5. Repeat step 4 for each additional concept, following our search worksheet:

a. For our second concept, enter: economy or economics
b. and for our third concept, enter: U.S. or United States or American

When you use ORs to search for all records containing any of the terms for a concept, you may create a very large set. Don't worry if the sets for any concepts are especially large. (The number of records will be limited later when the AND is used between different sets.)

Each time you do a search, you create a set of all records retrieved by that search. Many databases, such as the InfoTrac Searchbank databases, allow you to create a number of different sets and then use those sets in various subsequent searches to further refine your overall search process. These databases assign numbers to each set you create, so all of the records retrieved for the first concept you search should be listed as set 1, the records retrieved for the second concept would be set 2, and so on. Different databases use different methods for specifying a set number to search. InfoTrac labels each set with the letter R and a number-- R1 refers to the first set, R2 designates the second set and so on. (For other databases, refer to the directions for each specific database.)

Once you have created sets of records for each of your concepts, you should do a search to look for just those records containing at least one term from each of the concepts. To do this, you use the AND operator. You should first do a search for set 1 AND set 2. This search will produce a new set with a smaller number of records than either set 1 or set 2. If you have a third set, you can then do a search for set 3 AND the set created by ANDing set 1 and set 2. This will produce another set containing an even further reduced number of records. It is possible to AND more than two sets together in a single search (e.g. set 1 AND set 2 AND set 3,) but is generally advisable to just AND one additional set per search. This way you have a clearer idea of how much each set is limiting the search and you will be able to more easily notice if one set is limiting the search too much (e.g., resulting in no records retrieved.)

6. To find citations dealing with both our first concept and our second concept, click in the search box again and type: R1 AND R2, and then press Enter or click the "Search" button. The set that results from that search will be labeled R4.

6a. Since we have three concepts, enter: R3 AND R4 to find citations dealing with our first and second concept (R4) and our third concept (R3). The results of this search will be a set articles that are related to all three of our concepts.

When you have ANDed together the sets for all of your concepts, the resulting set of records should be narrowed down to your precise topic. Of course, when you actually look at the records, you may find that your search needs some further refining. One of your concepts may have limited your search too much, for example, or you may need to limit your search even further with an additional concept. Check the subject headings assigned to any records that seem particularly useful. You might find additional search terms to improve your search. Each time you do a search on a topic, it is important to analyze your results in order to try to find ways to further refine your search.

Truncation and "Wildcards"

It is common to find that several search terms identified for a single concept may begin with the same root. For example, for the concept "economy", you may also want to include "economic" or "economics" or "economist". Instead of listing all of these terms separately, many databases allow a search procedure called "truncation." The truncation feature lets you use a special character to search for any words beginning with a particular root. Common truncation characters used by many databases are the asterisk (*), the question mark (?), or the exclamation point (!). In our search example, we could use truncation to search for "economy" or "economic" or "economics" or "economist", by simply entering "econom*" in InfoTrac. It is important to be careful, however, when using truncation, because if you truncate after a short stem, you might retrieve words that you don't want. If you used "eco*" instead of "econom*", for example, you would also retrieve records with the words "ecology" or "ecosystem".

In addition to the use of truncation for words with same root but different endings, some databases allow the use of a special character, often called a "wildcard", in the middle of a word to search for spelling variations such as "adviser" or "advisor". The "wildcard" character would be used in place of the letter that may vary, e.g. "advis?r" would find either "adviser" or "advisor".

These materials may be used for educational purposes if you inform and credit the author and cite the source as: LSCI 105 Computerized Research. All commercial rights are reserved. To contact the author, send comments or suggestions to: Eric Brenner at brenner@smcccd.cc.ca.us