Slope function combined with some sort of lookup

Hi, I am wanting to calculate SLOPE on a data set where a common factor is present.

Eg. There are a number of employees, each with multiple clients. I have a list of all employees and want to calculate slope on the X & Y of just their clients.

I know there is an easy way to do this but i just cant work it out. Can anyone help?

Cheers,

Can you upload example?

Ok, here's an example.

For example, for John i want excel to look up all of John's clients, and automatically apply all of column C & D that applies for the Slope formula.

I'm thinking it can be done with some sort of Array formula but cant get anything to work.

I've saved it as a .xls for compatibility but i do have 2007.

Try this comfirmwd with ctrl+shift+enter:

=SLOPE(IF($A$2:$A$30=$F2, $C$2:$C$30), $D$2:$D$30)

Got it, thanks mate, you're a champion!!

The best answer probably on the web.
I needed to do several slopes for multiple ranges/criteria.

Finally can finish it. Thanks!