Taking Advantage of Operators

by Carl Heine, Ph.D.

Last fall in my report on five things that today's digital generation cannot do, I could easily have included a sixth problem area: using operators. The majority of students we've observed do not know how to use operators. What sets this problem apart from the rest is that operators are not entirely necessary. The right keywords in a powerful search engine like Google render operators almost useless. Almost, but not quite. AND has been replaced by the space between keywords. OR causes confusion. NOT is a risky choice. Placing "quotation marks" around words is not as essential as it once was. And not every search engine treats operators the same.

Bye-bye Boolean?

Information may be retrieved in multiple ways, and while operators provide additional leverage, they are simply not necessary most of the time. Using specific keywords in unique combinations works just fine in the majority of cases. So why bother with Boolean and other operators? The main argument for using them is that they can fine tune a search without having to rely solely on keywords to do all the work, which usually involves searching for increasingly specific combinations of words. Additionally, Boolean operators are still used by many specialized proprietary databases, so awareness of these classic tools remains important. Have an opinion? Let us hear it on our forum: Are Operators Obsolete?

Example 1 -- If I want to retrieve a history of all the reported North American sightings of Sasquatch, also known as Bigfoot, I could start with the query, history sightings sasquatch bigfoot. However, this query contains two closely related terms, sasquatch and bigfoot, and will retrieve pages with ALL the terms to the top of the list. Maybe the resource I'm looking for doesn't use both names for the legendary beast.

A more flexible query in this case is history sightings sasquatch OR bigfoot. I don't know which term might be used, and this guarantees an inclusive search. My first query retrieves the document I want (#8 of 52,900 Google returns); the second query returns it a little higher, along with four times as many results (#4 of 212,000 Google returns). As it turns out, I could have found the resource with or without the extra operator.

Example 2 -- "Quotation marks" eliminates the flexibility of AND and OR. If I want to find an EXACT match, placing two or more words in quotes will greatly reduce the number of documents retrieved. Using the query credible sightings sasquatch produces 14,200 results, and the site I want is #1. Placing quotes around the first two terms, the query "credible sightings" sasquatch now produces 526 returns, with the same #1 site as before.

If I thought "history of sightings" sasquatch would be a good query, Google comes back with only 102 returns, but the database I want is now harder to identify (it's in the top 10 but refers only to Texas sightings). I should be extremely confident that I know the right words to use before using quotes.

Example 3 -- NOT has an effect similar to "quotation marks", but less pronounced. It eliminates pages that contain a particular term. To search for a snowboard design known as the sasquatch, I could use the query snowboard sasquatch -bigfoot (note that Google requires the minus sign instead of NOT). The site I want is #1 out of 33,400. Without NOT, the query snowboard sasquatch retrieves 40,600 pages, although the page I want is still #1.

The risk of using NOT is that the page I want may contain the word bigfoot, in which case I would never find the information I need.

Without careful application, operators can actually prevent you from finding the information you need. This is where students encounter problems.

These examples illustrate what particular operators do and that each one helps a little. But without careful application, operators can actually prevent you from finding the information you need. This is where students encounter problems.

What Research Reveals

To find out how students think about and use operators, we collected query data from 60 second-semester sophomores at the Illinois Mathematics and Science Academy. Prior to any instruction on the effective use of operators, students were asked to enter keywords in the fields of an Advanced Search page to find information for a research project. In this case, JSTOR was used rather than Google--the research project required finding historical articles. JSTOR employs fields similar to Google: all of these words (AND), the exact phrase ("quotation marks"), at least one of these words (OR) and none of these words (NOT).

Results using AND -- This was the most commonly employed operator, used in 53% of the 208 recorded queries. It was also the only operator used correctly most of the time. In 64% of the cases, students entered words appropriately into this search box.	Percentage of mistakes made: • 60% -- using stop words in the query • 38% including the term AND unnecessarily
Results using "quotation marks" -- Students entered one or more terms in the exact phrase search box in 27% of their queries. The operator was used correctly in 46% of the cases. The most common mistake was using quotation marks with only one word, which has the same effect as using AND.	Percentage of mistakes made: • 74% -- entering only one word in the search box • 26% -- entering words that would have been more effective using AND or OR
Results using OR -- This operator was infrequently used (17% of the queries), but when it was, problems tended to occur. OR was used correctly only 40% of the time. Most of the errors were made by using words that are effective with AND. The result was a dilution of the effectiveness of students' keywords.	Percentage of mistakes made: • 58% -- entering words that should be used with AND • 21% -- using OR with only one term • 18% including the term OR unnecessarily
Results using NOT -- Finally, Students rarely turned to the NOT operator for help (only 3% of the queries). When they used it, 100% did so correctly.	Percentage of mistakes made: • 0% -- the NOT operator was used appropriately in all cases (However, in none of the cases was the use of the operator effective, since this is not the procedure for eliminating book reviews in JSTOR)

In the end, these operator mistakes made it harder for students to locate the information they needed. Despite this, some students persisted and found answers. The only mistake for which there was no work-around was searching for the wrong concepts to begin with.

The misuse of operators (without knowing it) can slow down a search unnecessarily and perpetuate myths about how search engines function. Therefore, we recommend that students be taught what each operator does and under what conditions each one should be used.

What you can do to help

Start by teaching students what can be done with each operator. For more background than is provided in this article, check out our basic and advanced video tutorials on operators, listen to the podcast with Chris Sherman in this Kit and check out these free online resources on operators.

Second, help students recognize when conditions are right to use an operator. When in doubt, it's best to stick to the standard ALL the words search box. The QuickPick article in this Kit provides tips on when to use each operator and offers opportunities to apply these tips.

Finally, help students master their use of operators with these Kit resources:

Curriculum--

• Three Operators to Know Chris Sherman talks about his choices for the three most useful operators that students should master.

• Action Zone Lessons unpacks how to use the Pirates and Piranhas games in this Kit

• QuickPick: Operator Smarts describes what each basic operator does and when to use it. Three practice examples are attached that may be used to test students' knowledge about operators and when to use them.

Action Zone--

• TV Search Challenge Using the right operators helps solve this live Internet Search Challenge: What television episode opens on a green planet with a red sky?

• Pirates and Piranhas Two different simulations help students identify important concepts in a research problem, select initial keywords, refine keywords and make decisions about using operators.

• MicroModule Companion: Operators This new tutorial teaches what basic and selected advanced operators do and when to use them.

Assessment--

• Operator Search Challenge If you are looking for a quick way to assess your students' knowledge and skills using operators, this tool can reveal what students know about AND, "Quotation marks," OR and NOT and whether they can apply each of them effectively in simulated and live searching.

• An Assessment Scoring Guide provides guidelines for evaluating students' performance. A pdf version is also available.