To test or not to test

As an HR person I try to be up to date with what is happening in this field, and these days I wondered about test during interview.

We all know that there are a lot of organizations that makes the decision to hire someone depending of the results of different tests.
We can use:

•  aptitude tests - that shows how well will a candidate complete his tasks for a particular job;

• personality tests - we can find out that the candidate personality match our organizations and out team;

• skills and knowledge tests -  used for finding out what skills and knowledge the candidate has for the job and not only;

• cognitive ability tests - measures the general mental capacity of the candidate;

• emotional intelligence tests - we can find out how well can he build relationships and understand others emotions.

But why should we use these test and why the results must count in our decision to hire the candidate or not?
To get to the answer I used PROS & CONS Analyses:

• using this tests, we eliminate the subjectivity of the recruiter;
• we can compare the candidates based on accurate results because the tests are the same for everyone;
• sometimes the unstructured interviews can't point all the important criteria that must be achieved by the candidate and a tests can give you the answers at some points that weren't reached in the interview sessions;
•  we can use tests that are strictly job related and we can see if the candidate has the skills we need for our vacancy;

CONS:

• all the tests have limitations. Per example: you can find a candidate that knows about tests and he can lie at some questions to get a better score. Job knowledge tests don't take in account one important attribute like learning ability;
• the test can't give you all the information about your candidate and you have to use others instruments. It can be other tests, or a discussion with him;
• the results of a test can be ambiguous and can't provide certain things. But in this case you can use a firm that is specializes in tests and they can assist  you understanding the results;
• good test, usually take more than 60 minutes and after you have to take time to see the results and we all know that time is important in finding and attracting a good candidate;

What is important when we use a test is to be sure that the test is legal, it is related to the job and is validated, otherwise you risk to have incorrect data.

Also you have to know that there is the possibility for the result to be false negative or false positive.

How much should the results of a test count in your decision to hire or not a candidate? 

From my point of view if you use a test you use also the result in your decision but you have to take care that this result isn't the breaking point in the final decision because you have to take into account that it is possible that the candidate had a bad day or he is an emotional persona and you can loose a good candidate.

One of the most important test that give you clear data are job knowledge tests that are made in our organization with the help of the team leader of the new employee and that shows you what he knows and if he is a match for your vacancy (ex. CAD test, Programming tests). From my point of view this is the test that has to count in your decision, the other test can give you some ideas of what kind of persona and it can confirm your observations during the interview and can that you have a solid candidate or not.

But what do you do when a candidate get a high score? Do you hire him immediately?  Maybe....or maybe not...you have to use more that one instrument or technique to be sure; you can use references from the former employers and colleagues.
Using test it definitely improves the quality of hire.
Example of tests: Belbin Test, tests provided by Hudson, Hogan test, D.I.S.C. test. (be careful because some tests need to be used only by an psychologist).

What do you think about this subject? Do you use tests in your recruitment process?