A person can have a great interview but essentially it is a performance. He/she is on her best behaviour, fulfilling a role, in order to secure a position.

Ensuring a potential candidate's personality is appropriate, and suited to a position, is as important as validating his/her relevant paper qualifications and skills.

Knowing this prior to hiring or developing someone allows you to have a better understanding of how he/she should be managed, thus reducing the potential for problems to arise.

Take a look at the following examples, what do they tell you? Which one is the computer software engineer and which one the sales person?

The top example is the computer software engineer and the bottom is the sales person.