Stephanie Webb ’13 left her bike locked to itself with a cable lock over winter break. When she returned to campus, her light pink Fuji was still parked outside her dorm, Florence Moore, but it was freshly secured with someone else’s U-Lock.

Another student, Lea Gee-Tong ’13, parked her bicycle outside the Palo Alto Caltrain station to visit her grandfather at the hospital in San Francisco. Though Gee-Tong locked her bike to a rack with a U-lock, she still found her bike missing four hours later.

The police told her “there wasn’t really anything that can be done, even if I had the registration number,” she said.

Their stories underscore the difficulty that faces campus and area police, who struggle to deal with theft on a campus of an estimated 12,000 bikes.

But officers have a theory about theft trends.

Stanford police officers said they see a correlation between bike theft rates and the county unemployment rate, suggesting the economic downturn may have had a greater effect on everyday life than they once thought.

According to Stanford Chief of Police Laura Wilson, as unemployment rates go up, the number of bike thefts also rises, and police officers can do very little to stop it.

“There is a remarkable trend,” Wilson said. “If you look at the graph of the unemployment rate in Santa Clara County, and you put the graph of bicycle thefts over that, there are remarkable correlations.”

According to the 2009 Stanford University Safety, Security and Fire Report, 297 bikes were stolen in 2007, 353 in 2008 and 351 in 2009. About 73 bikes thefts have been reported so far in 2010.

The January unemployment rates for Santa Clara County in 2007, 2008 and 2009 were 4.7 percent, 5.1 percent and 9.3 percent, respectively, according to the U.S. Bureau of Labor Statistics. The January 2010 unemployment rate is 12.1 percent.

The Department of Public Safety has conducted no formal study on the perceived pattern.

Wilson said the height of reported bike robberies occurs in September and October. She added that if students leave their bikes on campus over the summer, they typically report thefts after they return to the Farm.

William Larson, a spokesperson for the Stanford Department of Public Safety, speculated that the most frequently targeted areas for bike thefts are around student residences, the Main Quad and the Medical School.

Students can avoid becoming victims of bike thefts “by licensing and securing their bicycles in a well-lit and visible area,” wrote Larson in an e-mail to The Daily.

Larson said bicycles are usually stolen because they are not properly secured. He recommended that students secure their bikes to a bicycle rack with a U-lock.

Wilson, however, said U-locks may even be inadequate.

“It’s very easy to steal an unlocked bicycle,” she said. “It’s moderately easy to steal a bike locked with a cable lock, but even U-locks can be shattered.”

Wilson estimated that only three to five bike thieves are caught each year.