A few missed paychecks.

For some families and individuals in Santa Cruz County, that's all that stands between a roof over their heads and an uncertain existence -- a month couch-surfing with friends, maybe a week in the car, then a shelter or camping out in some out-of-the-way spot.

The most recent look at homelessness in Santa Cruz County -- a count and survey conducted by the United Way of Santa Cruz County and the nonprofit research firm Applied Survey Research -- shows that the homeless population in Santa Cruz County has jumped 22 percent in two years. There were an estimated 2,771 individuals without homes in the county in January, according to the homeless census. The tally in 2009, the last time a count was taken, was 2,265.

The major causes, the report concludes, are what you would expect: a sputtering economy in which many people are being jettisoned from once stable jobs coupled with increasing local rents. As homes prices fall, and more people purchase homes to live in, rents on those remaining rentals inch up.

But homelessness is complicated, and attributing it solely to hard economic times does not fully explain what is a vexing community problem. That's part of the value of the census and survey.

It's not just one number -- or one conclusion. The report looks at many things -- the ages of the homeless, where they come from, the benefits they use, the problems that landed them on the street. It offers interesting glimpses into the problem.

Among them:

Numbers can be deceiving. This year's homeless figure is 2,771; the number is based on a count by about 50 volunteers who fanned out countywide to places the homeless are known to gather. But experts then extrapolate those point-in-time numbers and conclude there are actually closer to 9,000 people homeless in the county at any given time.

Addiction plays a role. Sixty-three percent of the roughly 500 people surveyed reported having disabling conditions. The most-cited condition [38 percent] was alcohol and drug abuse, followed by depression and other chronic health problems.

Few would argue the homeless have it hard on the streets, but the numbers are alarming. According to the federal government, the average life expectancy of an American is 78 years. The average life expectancy for someone without permanent housing is between 42 and 52 years.

The majority [65 percent] of those surveyed receive some sort of government assistance, with food stamps overwhelmingly the assistance used most.

Contrary to what you see in the online comments on most any Sentinel story on homelessness, the majority of those on the streets are not out-of-county residents who came to the area to take advantage of local services. Sixty-seven percent of survey respondents indicated they were already living here when they became homeless.

Homeless parents are like most all parents, fighting to do right by their kids. Ninety six percent of homeless parents with school-age kids in tow had those kids in school.

Young adults look to be increasingly affected. There were 99 young people without shelter in 2011 compared with 34 in 2009.

There can be a legacy of homelessness. The data showed 23 percent of homeless youth reported at least one parent was or had been homeless.

Homelessness was up in all cities in the county except for Watsonville, which saw a slight decrease from 561 people to 530.

Santa Cruz had the highest number with 1,070, up 169 from 2009. Scotts Valley went from no homeless to 13.

While the jump in homelessness in the past two years is disappointing, homelessness in the county is still down from a count of 3,371 in 2005.

The biannual census is required for the county to receive $1.7 million in federal homeless-assistance funding annually. But another important facet is its ability to change the debate around the local homeless problem.

It reminds people that there are many roads to the street, that it's unfair -- impossible actually -- to stereotype the homeless. They're young, they're old, with kids and without. Maybe they're struggling with addiction or suddenly jobless. Maybe it was just a few missed paychecks