Federal Reserve Increase May Not Affect Southern California Housing Market.

Byline: Michael Rappaport

Apr. 25--For many would-be home buyers, the important number when deciding whether or not they can afford a particular home isn't the overall price.

It's the payments.

It's the amount a buyer will be asked to fork out every month for the next 30 years -- the mortgage payment -- that determines for most people how much house they can afford.

That's why mortgage rates matter. Depending on what size loan a buyer is seeking, a difference of 1 percentage point -- 100 basis points -- can mean hundreds of dollars more on a monthly payment and hundreds of thousands of dollars more over the course of the mortgage.

Anyone who watches television or listens to the radio has heard countless ads the last few years on …