Finding the best candidates for a job opening is a process of elimination. Information filtering is used to bring candidates or aspects about them to our attention. Specifically in recruiting, filtering information with a computer introduces a high risk of losing the best candidates. Here I discuss the filtering of candidates from an available pool generated i.e. through marketing or from an existing resume database.

The search process is a path of four stages from a potentially large pool of candidates to a single individual who will be offered the position. Each stage involves the elimination of candidates based on missing qualifications. Information filtering plays a key role in this process. For the receiving employer the recruiter is the information filter. The search stages are:

1. Search an electronic database for qualified candidates
2. Evaluate resumes and cover letters,  research information about candidates on social networks and other online resources
3. Conduct phone interviews
4. Conduct in-person interviews

The graphic illustrates the impact of filtering information on the size of the pool of remaining candidates in each stage.
Fig.1: Filtering Candidates from a Pool



1. Search an electronic database for qualified candidates
This stage involves the filtering of candidate information (screening) from an electronic database. Three aspects are significant:

• A recruiter's best candidates are in this pool. It is therefore paramount not to overlook them.
• This stage produces the highest elimination rate. Typically more than 90% of your candidates are eliminated here. Only a small number of candidates make it to next stage.
• The impact of technology is very high. A human is the best filter but recruiters often don't have the time to read every resume due to the volume of candidates for the job. For this reason the filtering of candidates is delegated to a database by searching with keywords, boolean logic or other tools.

The question is whether the best candidates will make it to stage 2 if the computer filters the resumes. A computer has extreme difficulties analyzing unstructured information like resumes. Hence when this task is delegated to the computer it is handed off to someone with very limited abilities. Yet the decisions the technology makes for us eliminate the vast majority of candidates from the pool without us knowing what we are missing.

2. Evaluate resumes and cover letters, research information about candidates on social networks and other online resources
We arrive at stage 2 with a much smaller pool of candidates. Depending of the success of stage 1 the best candidate(s) may or may not be part of this pool. During this stage all resumes and cover letters are manually read and evaluated. As stated above a human is the best filter with the least potential for error. For this reason a recruiter will spot the best candidates in this remaining pool. Additional electronic resources like social networks and background check databases are queried. Assuming that the data from these resources is valid for the recruiting purpose it depends on the search tool whether we will overlook important information. The best databases have highly defined and structured information that can be looked up through selection screens. Unstructured search with keywords bears the highest risk that we miss important information.

3. Phone interviews
The field of candidates is shrinking.  At this point there are less than 5% of the candidate from the original pool left. A recruiter uses information gathered during the previous stage to evaluate soft and hard skills of candidates in a conversation. Candidates are filtered by a recruiter, not a computer (compare stage 1).  Success depends on the qualities of the recruiter and knowledge of his/her customer.

4. In person interviews
The last stage of selecting the successful candidate involves the highest degree of scrutiny.  Only few candidates make it here. They meet in person with the recruiter and/or employer staff. It is the highest grade of filtering but also the most time consuming.

Conclusion
The first stage is most important in the search process. Here is determined whether it is worth to spend the time and effort on the subsequent phases. Only if the best candidates can get the recruiter's attention by making it through the electronic screening, the recruiter may have the candidate who will get the job offer. The dilemma is that while it is the most important stage, recruiters have the least amount of control over it compared to the rest of the process.