I'm no expert, but from my experiences they tend to run these tests to give them some sort of 'scientific' evidence for use at interview. Let me explain;
If for instance your profile results said you were (relatively) weak in a particular area, that would be something that might warrant further inspection during interview. Lets say you appeared to lack ambition. They may ask you at interview where you see yourself in a few years time, asking about what you want to achieve, areas you may see yourself progressing into etc. This may allay their fears or confirm them!
I had just such a scenario, which I was told about after I had been given the job. My results said I lacked ambition, but put into context once I had been questioned at interview it was clear there was good reason for this; I had been under threat of redundancy for nearly 12 months after 9/11, loaned out for the summer with no leave entitlement, a baby on the way with suspected birth defects (turned out fine), big mortgage, wife, two other kids ..............etc etc. On debrief the HR Director said it wasn't really surprising that my long term career goals weren't at the forefront when I answered the profile questions!
So you see the profile is just another tool to try to get to the 'real' you, just like a Maths or English test, a spatial reasoning test, even a sim ride. Usually a profile is not taken in isolation and used to chop a candidate, whereas the other 'paper' type exams may be. It's a cost thing. It's relatively cheap to run a days testing in a classroom for thirty applicants and to run Maths/ English/ Spacial Reasoning type tests and to possibly sit the profile and group type tests too. The expensive part is the interview (time consuming as you can't really do a group interview!) and sim assessment (for obvious reasons!), so airlines will tend to use the cheaper tests to see which candidates meet a certain base level before offering the more expensive tests to those successful at stage one.
Regards
PP
ESTJ
