The "Big Five" model of personality has become the basis for many personality assessments. Many companies these days even have potential employees take the test as part of an application process. The model is very popular but is it truly a reliable test of personality?
The first question i raise is what is personality? Personality is an abstract construct. How can one measure it and give it a numerical value when it is not even clearly defined? I think these kinds of test can be helpful to tell us more about ourselves. What it cannot do is give a definitive answer on who we are. These tests are not falsifiable. How can you give a numerical vale to how open one is to new experiences? I call shenanigans.
Another aspect i question is the way the tests are given. Not every person will interpret the question the same. If each person will take the test in a different way how can the "Big Five" test be considered reliable? Also, when given for interview purposes, clever individuals will simply answer the question to what they think the company prefers. I think the test is at its peak when it is taken alone and the results are only seen by the test taker. This way the person taking the test has no other motives to answer the questions to anyone others preference and will really be able to look inward at themselves. This way the test more accurate. Companies who give this out as part of an applicant process are really just kidding themselves. If you really want the best employee you can get and want to know their personality, give the person a good ole fashion interview and find out for sure!