Well incentive/commission on new leases is really just part of the pay for leasing consultants. If you're doing well to capitalize on any and all traffic to lease your apartments your incentives/commissions are higher which in turn makes your pay better, and also it's the job you're entrusted to do. As for the specific apartments, some are hard to sell, whether location, upgrades, comps are lower, etc. I think adding an incentive to it makes those in charge of renting be more creative and break the normal routine used to lease. I'm not sure the efficacy is totally measurable. You are right about lots of variables. It's all about the apartments getting rented, and the residents and staff being happy.