Take a good look at that store on the corner. There is a 10 percent to 12 percent chance it will not be there next year, according to the Office of Advocacy for the Small Business Administration.

“If you’re new you have about a 50-50 chance of surviving five years,” said Brian Headd, an economist with the Office of Advocacy, which tracks small businesses and examines the impact of proposed regulations on them.

Still, such odds do not seem to damp the desire of entrepreneurs.

An estimated 671,800 small businesses with employees opened their doors in 2005, the most recent year with statistics available, even as another 544,800 were expected to close theirs that year.

“Starting a business is actually easy. You can get business cards and an address at Mailboxes, etc.,” said Bill Morland, chairman of the Orange County chapter of Score, a nonprofit association that works with the S.B.A. to educate and assist entrepreneurs. “But you’re not really in business until you sell something, and that isn’t easy.”