We consider it to be fairly marginal, given that a $10,000 tax credit translates into $1,500 in tax savings in the year of purchase, or in subsequent years, if there is no net tax liability.
For purchasing a property worth $200,000, $300,000 or more, the impact will be marginal. We don't think it will be enough to encourage many people to stop renting and become homeowners.
That's why we didn't include a behavioural effect. Again, we could be wrong, because there are certainly going to be people for whom this will be the incentive they needed. However, we don't believe that the effect is measurable or dramatic enough to change our cost estimates significantly.