The Beginner's Guide to Boolean Search Operators

Siofra Pratt
Posted by Siofra Pratt,
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On Monday, we (along with Google) celebrated the 200th birthday of a very special man – Mr. George Boole. George Boole was a British mathematician whose work on logic laid many of the foundations for the digital revolution. His legacy was Boolean logic, a theory of mathematics in which all variables are either “true” or “false”, or “on” or “off”. This logic still underpins all digital devices, existing in almost every line of computer code, and it just so happens to be the means by which recruiters everywhere search for candidates on the likes of LinkedIn today.

Boolean search writing is a skill that top recruiters need to know directly in order to get meaningful candidate search results from a wide range of software, and is therefore, a core skill you need to develop if you wish to be a successful recruiter. However, fully constructed Boolean search strings can look both confusing and complex, and therefore, difficult to write. But don’t worry, because they aren’t! And we’re going to teach you why they aren’t today.

What is Boolean Search?

Boolean Search is a way to organise your search using a combination of keywords and the 3 main Boolean operators (AND, OR and NOT), to produce more accurate and more relevant results for your candidate searches on LinkedIn and beyond.

The first important thing to appreciate about Boolean, is that there are only 5 elements of syntax to understand. These are:

  • AND
  • OR
  • NOT
  • ()
  • “”

By applying these appropriately, along with the keywords you wish to consider, you can create a huge range of search operations. There is no limit to how often you can use any of these elements in a search, so you can create very specific search strings, which will save you a lot of time in filtering the results.

The AND Operator

boolen search

Take these 2 groups. In the first group are all the people who have the keyword “recruitment” somewhere in their LinkedIn profile. In the second, are all the people who have the keyword “HR” somewhere in their LinkedIn profile. When we use the Boolean string:

Recruitment AND HR

We are asking the LinkedIn database to search for all of the people who include both the word “recruitment” and the word “HR” on their LinkedIn profile. Meaning we are only looking to find candidates who fall in the cross section of the Venn diagram – candidates who have both keywords mentioned in their profile:

boolen search

The more criteria we add using the AND operator, the less people we will find with our search, because by using AND we are narrowing our search. However, the people we do find from our search will be more relevant, as they will possess both of those skills.

The OR Operator

boolen search

In this example, one group of people have the keyword “Recruitment” in their LinkedIn profile, while the other have the keyword “Recruiting”. Both words mean exactly the same thing to you and I and anyone using either of the two terms to describe their job function or skillset on LinkedIn possessing exactly the same skillset, but to an electronic database they are totally separate terms. When we use the Boolean string:

Recruitment OR Recruiting

We are asking the database to search for candidates who include either of the two terms in their LinkedIn profile, or both terms simulatneously. Meaning we are looking to find candidates who fall in either side of the Venn diagram or indeed, the cross section:

boolen search

Therefore, by using OR we are broadening/expanding our search to encompass profiles that have one result or the other or both.

Using OR enables us to find hidden talent e.g. people who have expressed their skills and experience in a different way than you might normally search e.g. banking OR bank OR finance OR financial, because by using OR we are broadening our search.

The NOT Operator

boolen search

Like in the first example we used, one group of people have the keyword “Recruitment” in their LinkedIn profile, while the other have the keyword “HR”. When we use the Boolean string:

Recruitment NOT HR

We are asking the database to search for candidates who have the word “Recruitment” in their profile, but to exclude any candidates that also have the word “HR” in their profile and those who just have the word “HR” in their profile. Meaning we are looking to find candidates who fall just on the right-hand side of the Venn diagram:

boolen searchUsing NOT enables us to remove false positives from our candidate searches, as by using NOT we are filtering our search and removing irrelevant results:

REMEMBER: Each of the 3 Boolean operators should always be written in UPPER CASE. If not, they will not work.

Brackets ()

When using Boolean search, there is no way to determine how the computer will solve our equation. This means that in order to get the most relevant result for us, we have to use something called parentheses to tell the computer what to solve first. This is where using brackets comes into our Boolean search.

Using brackets is essential for writing complex search strings, but it can be their application that causes the most confusion amongst recruiters. Essentially, a clause within brackets is given priority over other elements around it. For example, if I was given the following search:

talent OR hr AND recruitment

Do I mean to say I want to find someone who has either the keyword “talent” or the keyword “HR” on their profile, and has the word “recruitment” too? Or do I mean that they have to have “talent” or the combination of “HR” and “recruitment”? You see, the absence of brackets makes it impossible for the database to know what you mean. Watch how the meaning changes when you add brackets.

In the following example, I have told the database that I need to find someone who has either “talent” or “HR” or both, and that they also need to have “recruitment”:

(talent OR hr) AND recruitment

But in the following example, I have told the database that I need to find someone who has “talent” or a combination of “recruitment” and “HR”:

talent OR (hr AND recruitment)

The most common place that brackets are applied by recruiters is in the use of OR strings. Basically, if you’ve written OR somewhere in your search, think about where the brackets will go because their placement will affect how the computer solves your Boolean search query, which will affect search results you receive back.

Quotations “”

When using Boolean search, if the keyword you’re searching for needs to be considered as a whole word e.g. Gas Engineer, then it must be enclosed within quotation marks in your Boolean search string. If not, the database will consider the space between the two words to be an AND and will search the database for two terms – gas AND engineer – and not what you want to search for which is the exact phrase “Gas Engineer”.

In other words, you must use quotations wherever you have two or more words as a phrase in your Boolean search string that you know for certain should be right beside one another like “Information Technology” or “Human Resources”, as quotations define a number of words as one exact term.

 

Today, we’ve explained the basics of Boolean – the bread and butter if you will – which I hope helped you gain a better understanding of the fundamentals of Boolean search and made it less daunting to tackle in the future. There are, of course, several other Boolean modifiers you can use to further refine and improve your Boolean searches, as well as many more rules for the use of Boolean in various other search engines and databases beyond LinkedIn.

So, for a complete and truly comprehensive guide to mastering the art of Boolean search, you need to take our Black Belt in Internet Recruitment online training course. In it you’ll find our Search Basics module, where you will not only learn the basics of Boolean search including all the different operators, modifiers and rules, but you will also learn how to plan and research your searches using our unique Universal Search method, how to research synonyms, location and language searches, how to search Monster.com’s extensive database, and how to search Indeed.com, the world’s number one job site. For a preview of the module and all it has to offer, request a demonstration with a member of our Sales team today by clicking here.

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