Interview, look for personal letters and testimonials- and you should be able to call those people and check that they really wrote the letters. In addition, make certain that your agent gives you a service guarantee- that if you aren't happy, you can cancel the contract. I give one to every one of my clients- after all, if I am confident in my abilities and my service- why wouldn't I guarantee it? Many of the "biggest" agents require that you stay with them 12 months if you sign a contract.
I'd love to have the opportunity to interview with you about selling your home!
Factors that I would consider are the sold properties average market time, sales price compared to the area, the agent's willingness to advertise and willingness to return your calls.
If you still want the sales per agent (maybe to avoid super-high-volume agents :) ), send me an email at Ted@UltimateSanDiegoHomes.com and I'll happily look it up for you.
The stats they will give you will be for the agents paying them for their services
it's important to know that per our local rule, only the agent who listed the home may say they "sold" the home.
Liz makes an important point, equally important as knowing the number of homes sold is to know the percentage of homes sold versus listed (how many listings expired) and also the time on market. it's good to know also what the percentage of deals "double ended" was...that is, how many of the homes that were sold were their own listings...i.e. no cooperating agents, just them, all by their lonesome. I'm not sure if the stats feature can crank out that info without a bit of effort.