Why Boolean Search is Such a Big Deal in Recruiting

In the past, I’ve explained the Boolean Black Belt concept and exposed what I feel is the real “secret” behind learning how to master the art and science of leveraging information systems for talent identification and acquisition.

Now I would like to show you precisely WHY Boolean search is such a big deal in recruiting.

There are 2 main factors:

  1. Candidate variable control
  2. Speed of qualified candidate identification.

The goal of this article is to shed significant light on the science behind talent mining, how it can lead to higher productivity levels (more and better results with less effort), why I am so passionate sourcing, and why everyone in the HR, recruiting, and staffing industry should be as well.

Control is Power

Talent identification is arguably the most critical step in recruiting life cycle – you can’t engage, recruit, acquire, hire and develop someone you haven’t found and identified in the first place.

My experience has shown me that properly leveraging deep sources of talent/candidate data (ATS/CRM’s, resume databases, LinkedIn, etc.) can enable recruiters to more quickly identify a high volume of well matched and qualified candidates than any other method of candidate identification and acquisition (e.g., cold calling, referral recruiting, job posting).

The true power of Boolean search lies in the intrinsically high degree of control over critical candidate variables that using Boolean strings to search deep data sources such as resume databases, the Internet, and social media affords sourcers and recruiters.

Applying that that high degree of control to large populations of candidates – tens of thousands (small internal ATS, niche resume database) to tens of millions (large ATS/CRM, Monster resume database, LinkedIn, etc.) enables adept sourcers to perform feats of talent identification and acquisition most would think impossible.

Candidate Variables Defined

The match between a candidate and a specific job opening can be expressed as a combination of these 5 basic variables:

  1. Location
  2. Skills (Experience/Education)
  3. Opportunity
  4. Compensation
  5. Availability

There are certainly other factors at play when it comes to determining the right match between a candidate and a particular opportunity (e.g., cultural fit). However, these are the “big bucket” variables which render the rest pointless if they are not satisfied.

Control What You Can

Ultimately, the best match between an employer’s hiring need and a candidate is one where there is very close alignment between a candidate’s variables and those of the particular job opportunity.

Most job openings have a fixed set of variables – sourcers and recruiters don’t often have the opportunity to control or change the location of the position, the skills/experience/education required, the specific opportunity (the type of work involved in the position, the company/team culture, opportunities for growth/advancement, etc.), the compensation associated with the position, and when the position becomes available (open and ready to hire).

However, when it comes to searching deep sources of human capital data that support Boolean queries (such as your ATS/CRM, online resume databases, LinkedIn, etc.) to identify potential candidates for any particular job opening, sourcers and recruiters CAN exercise a significant degree of control over critical candidate matching variables.

Here’s a preview:

Controlling Candidate Variables Through Boolean Search


When it comes to using resume databases (internal or online), sourcers and recruiters have nearly complete control over the location of the candidates identified – finding people in specific zip code ranges or by using a combination of area code and address search.

A small percentage of the time, candidates with resumes not updated in the past 6-12 months may have moved from the address on their resume, but this is a fractional minority.

Although using Boolean search strings to identify candidates in resume databases or online affords specific control over the location of candidates identified, there is less direct control over the commute tolerance/preference of the candidates – that can only be reliably determined by contacting each candidate.

However, sourcers and recruiters can target people who live very close to the location of the job opportunity (5-15 miles), increasing the likelihood of solving the commute variable.


Sourcers and recruiters can run Boolean strings when searching resume databases to precisely target specific experience, years of experience, education, certifications, environment/project, and industry experience.

Those who are particularly adept at Boolean search can even achieve semantic search by crafting Boolean strings that go well beyond buzzword matching and target specific responsibilities, or in other words, what the candidates have actually done as well as what they have done it with.

Although resumes are far from a perfect medium for accurately or wholly representing skills, experience, and capability, a well stocked resume database affords sourcers and recruiters the ability to run Boolean queries to quickly find candidates with highly specific experience closely matching the required skills and experience of the position being recruited for.

Desired Opportunity

Although sourcers and recruiters using Boolean search strings to mine talent from resume databases cannot precisely predict what candidates will want to do in their next career move, a resume or very detailed social media profile often affords significant insight into a possible “career trajectory.”

In other words, a project manager over software development is likely to be interested in a similar role, or one that is a slight step up in responsibility.

Similarly, a 3 year staff accountant is likely to be interested in a role as a staff accountant, or perhaps the next step up.

Adept sourcers and recruiters can run Boolean strings to specifically target candidates who have experience similar to the work to be performed in the role being recruited for, increasing (but certainly not wholly controlling) the chances that candidates identified would be interested in the type of position they are recruiting for.


As with the opportunity variable, sourcers and recruiters cannot precisely control the compensation requirements of candidates identified.

However, resumes do enable recruiters to predict, to some extent, the desired compensation of candidates based on years of experience and market knowledge, and sourcers and recruiters can run Boolean search strings to target candidates with specific years of experience.

For example, in a given metro area, recruiters are likely to know what staff accountants with 3-5 years of experience (or software engineers with 3-5 years of Java programming, etc.) are being paid by most local employers, and from experience, what those types of candidates are looking for in terms of compensation when making a career move.

Although this is certainly not precise control, it does allow some degree of control. Also, when reviewing resumes in a database, recruiters can make the educated decision not to call candidates with 10-12 years of accounting or Java programming (unless they want to ask for referrals), and specifically target and contact candidates with 3-5 years of experience instead.


When searching databases and online sources of candidates, there is no way to reliably predict or control whether or not people identified via Boolean search strings are available or open to make a career move at the time they are identified.

However, when using online job board resume databases, searching for candidates with resumes posted within the past 30 days does increase the probability that the candidates identified are looking (actively or passively) to make a career move.

Statistically, anyone whose resume is hasn’t been updated in the past 30 days is likely to be a passive candidate, or not actively seeking employment opportunities. However, that doesn’t mean they aren’t recruitable.

In Comparison: Cold Calling and Referral Recruiting

While cold calling and referral recruiting are tried and true methods of identifying talent, and I would never suggest that they be avoided – I’d like to expose the intrinsic ROI limitations they afford sourcers and recruiters, primarily the inability to control critical candidate variables.


When it comes to cold calling into companies to source and identify potential candidates, there is very little control over where the candidates live. When calling into a company, you know where the candidates work, but the candidates could live anywhere within a 20, 30, 40, or even larger mile radius from that company location – in ANY direction.

Because there is no way to know exactly where the people you are calling live prior to sourcing them, there is no way to significantly control the Location variable of the potential candidates, and each person identified will likely have a different commute tolerance/preference which is based specifically on where they currently live, not where they currently work.

As for referral recruiting, when we ask other people who they would recommend – we can neither control where the potential referred candidates work nor where they live, so there is even less location-specific control offered by referral recruiting over cold calling.


When cold calling into companies or referral recruiting to identify candidates, there is no way to predict or control what each person identified will be most interested in doing in their next career move.


When cold calling into companies or referral recruiting to identify candidates, there is no way to control or predict what each person’s current compensation is, nor is there any way to predict their desired compensation. Even sourcing by title will not accurately or consistently predict the years of experience and specific responsibilities of each person identified prior to contacting them.


When cold calling into companies or seeking referrals in an effort to identify potential candidates, there is no way to predict or control each person’s capability to perform the responsibilities of the position being sourced for. Although you could ask for someone if they can recommend/refer to you a person with a specific title or experience, you simply can’t control actual experience of the people referred or identified, nor is there any way to control their career history, years of experience, education, or certifications.

The one aspect of experience/capability that can be controlled through cold calling is industry-related experience – if you call into a pharmaceutical company, you can be assured that everyone you identify has experience working in the pharmaceutical industry.

However, the same cannot be said for referral recruiting, as there is no reliable way to control the specific industry of the people who are offered as referrals.

Either the people you are seeking referrals from know of someone with the appropriate skills and experience and will recommend them to you or not. In either case, you are not the one in control – you are completely dependent upon each person you attempt to network with.


There is no way to reliably predict or control whether or not people identified via cold calling and referral recruiting are available or open to make a career move at the time they are identified.

Although you could ask people if they can recommend people who might be looking, whether or not they actually do know people who might be looking to make a change is not under your control, and the specific availability status of any referred candidate cannot be predicted or determined prior to actually speaking with the candidate.

Job Posting

For sourcers and recruiters – posting a job affords absolutely no control over critical candidate variables, as you are 100% at the mercy of other people finding and responding to the posting.

Anyone with any experience in the HR/Recruiting/Staffing industry knows that very few people who apply to positions are well matched across the 5 critical candidate variables with regard to the position they apply for. When you post a job online, you simply cannot control who will respond, what their skills/experience/education will be, or even where they live.

While not truly representative of any degree of control, when people respond to a job posting – it is often because they are actively (or perhaps passively, depending on your definition) looking for a change of employment from their current employer or their unemployed status. After all – if someone is looking at job postings, they’re considering their options to a lesser or greater extent.

So if your sourcing and recruiting strategy targets active candidates, this is the only bright spot when it comes to using job postings to identify potential candidates. However, just because someone responds to your job posting – it does not necessarily indicate that they are truly and unconditionally available to make a change.

Candidate Variable Control: Comparison of Sourcing Methods

In review, let’s take another look at the comparison of sourcing candidates via Boolean search vs. cold calling, referral recruiting, and job posting as with regard to the degree of control over critical candidate matching variables for talent identification:

Using Boolean search strings to identify and mine talent from private and online sources of talent empowers recruiters with the ability to apply a significant degree of control over the location, skills, experience, education, opportunity, and compensation candidate variables – more than any other method of talent identification.

Speed of Qualified Candidate Identification

The second piece of the puzzle that explains why sourcing via Boolean search strings coupled with deep sources of candidate data (resumes and detailed social media profiles) is so powerful is the speed at which candidates who closely match the critical variables of a given position can be identified.

Sourcing via Human Capital Data

Sourcers and recruiters who are competent at crafting Boolean search strings can find quickly find a large volume of candidates that are likely to closely match the 5 critical variables of the position they are seeking to fill.

I’ve personally achieved, as well as trained other recruiters to achieve, anywhere from 20-60 well matched candidates identified per hour mining talent with Boolean search strings (20/hour for a very challenging position to 60/hour for positions/skills that are more common).

I’m talking about finding 20-60 people in 1 hour who have the skills, experience and education required for the position I’m recruiting for, live in a commutable radius for the location of the position, are highly likely to be attracted to the opportunity, and who are highly likely to be within the compensation range of the position.

The only thing left to do is establish contact and a relationship with them, and attempt to solve the final variable – availability (whether they would accept an offer for the position if they interviewed well and felt it was a strong match).

Cold Calling/Referral Recruiting

While cold calling into companies can produce results, it is a slow and laborious process.

Cold calling into companies can in some cases quickly yield a high volume of names, but the intrinsically low degree of control over critical candidate variables that cold calling affords sourcers and recruiters severely limits the speed of identifying candidates who closely match the position being recruited for.

Referral recruiting, for many reasons can in produce some of the best candidates – most companies are proud to brag about the large percentage of referral hires they make.

However, referral recruiting is also a slow and unpredictable process – not every person contacted will yield a referral, and even those that do are not statistically likely to closely match all 5 of the critical candidate variables.

Job Posting

When it comes to posting jobs to identify potential candidates, it’s similar to setting a trap. It’s a 100% passive strategy – the only thing you are in control of is setting the trap.

You cannot control what, if anything, actually wanders into your trap, or if anything ever does.

It’s the same with posting jobs – some jobs never get any responses. Others do get a large influx of candidate responses, but the probablity that any given person is a close match across the 5 critical candidate variables is intrinsically low.

Speed of Qualified Candidate Identification: Comparison of Sourcing Methods


I hope you now have a much deeper appreciation of the “method to the madness” behind sourcing candidates via Boolean search strings and understand why Boolean search is such a big deal in recruiting.

There are tangible reasons why using Boolean strings to search private and online repositories of candidates can enable sourcers and recruiters to identify and recruit more well qualified candidates at a faster rate and a higher volume than any other method of candidate identification.

Quality X Quantity X Quickness = Results.

Although cold calling and referral recruiting are proven and viable methods of candidate identification (and I would never recommend not performing them), there is no denying that they do not offer sourcers and recruiters a much (or any, in some cases!) control over critical candidate matching variables. They are also intrinsically slow methods of identifying precisely matched and qualified candidates.

Undeniably, talent mining via Boolean search strings affords sourcers and recruiters the ability to exert a high degree of direct control over the specific location of candidates, the skills, experience, and education of candidates, as well as the ability to specifically target candidates who are highly likely to be interested in the opportunity being recruited for, and the compensation offered by the opportunity.

Imagine being able to find a minimum of 20 people in less that 1 hour of research who have the skills, experience and education required for the position you’re recruiting for, live in a commutable radius for the location of the position, are highly likely to be attracted to the opportunity, and who are highly likely to be within the compensation range of the position. The only thing left to do is “smile and dial!” If this sounds crazy or impossible – trust me – there are people who can do this day in and day out.

LinkedIn, the Internet, job board resume databases, and most corporate ATS/CRM databases are huge repositories of candidates – many companies have hundreds of thousands to several million resumes stored in their internal resume database. The major online job boards all have 20M+ resumes each, and often have over 100,000 resumes in each major metro area. LinkedIn has over 40M profiles worldwide, and 20M in the U.S. alone.

Large databases afford sourcers and recruiters to benefit from the laws of statisitcs with regard to large sample sizes. If a recruiter or sourcer were looking to hire for a rare skillset or combination of skills and experience that represented only 1/2 of 1% of the available candidates, and they had access to a resume database of 100,000 local candidates – 1/2 of 1% of 100,000 is 500 people. Eye opening, isn’t it? If you ever find yourself thinking you’re working on an impossible position, always remember the candidates you’re looking for actually DO exist, in more numbers than you would perhaps like to believe. You just need to figure out how to find them!

Sourcing candidates via Boolean search strings has the distinct advantages of speed, volume, and controlled accuracy of match across multiple and critical candidate variables which can enable recruiters to perform Just-In-Time delivery of well qualified candidates with less effort. The speed and match precision of searching for candidates with Boolean search strings effectively allows recruiters to produce more accurate results in less time, increasing productivity and reducing response time. Using proven Boolean search/information retrieval best practices, the probability that any given call will produce the right match is intrinsically higher than any other method of recruiting (cold calling, referral recruiting, networking, user groups, etc.).

Everyone will have their own opinions about the pros and cons of cold calling, referral recruiting, and sourcing via Boolean queries and which one is the superior method of talent identification – that debate will rage on indefinitely.

However, there is no denying the objective and intrinsic advantages of precise control over critical candidate matching variables and high speed identification of accurately matched candidates that sourcers and recruiters adept at wielding Boolean search strings can achieve when coupled with a resume database of a decent size.