If you mark your time on earth by the decennial census and, yeah, that would be weird it's about time to put another notch on the door frame. A form for the 2010 census should arrive in your mailbox Monday or a day or two after.

This is the big push for a process that takes years of preparation to pinpoint the national head count on a particular day in this case, April 1.

Maybe you noticed the $133 million ad campaign from the census -- including $2.5 million for ads during the Super Bowl -- that some marketing experts have called a flop. Census leaders consider it money well spent if it increases the number of people who fill out the form without a door-to-door visit from a census worker. Every 1 percent increase in the mail response rate saves about $85 million in census-takers, said William Hatcher, the regional census director, in a statement Thursday.

Months from now, the results will begin rolling out, telling us how we as a nation, as a state, a city, a community, even a neighborhood, have changed.

Roanoke will learn if its mission to increase population worked. The city's long population decline appears to have reversed. The U.S. Census Bureau estimated 2008 population at 92,697, a gain of 1,415 from 2006. Most of the rest of the region has steadily grown and we'll see whether that trend continues.

We'll also learn who's moving into the city. Are they old, young, black, white, Hispanic, male, female? Do they live in downtown, or out near Countryside, in Eureka Park, or in Raleigh Court?

The answers matter in a city like Roanoke, trying to maintain a healthy balance of residents. Are these new people in the city young people who expect a vibrant Roanoke, or empty-nesters less interested in change?

Are they professionals who earn well, spend aggressively and fuel the tax base? Or are they low-income families who pay less in taxes, but still depend on the same schools and services as everyone else?

Here are some questions and answers to consider as you prepare to be counted.

When will the form arrive?

Forms should arrive in mailboxes March 15 to 17, though in our region some residences in Craig County with post office boxes will receive the form hand-delivered by a census worker.

What's in the form? What do they want to know?

The form has 10 basic questions regarding the number of people living in a residence, along with age, gender, race, Hispanic origin and the relationship of each person to the householder. The form also asks for a phone number so a worker can contact you to clarify your answers.

How long will it take to fill this thing out?

An advertising blitz by the census bureau touts it as a 10-minute process. The real answer depends on how many people are in your household. Tammie McGee, a U.S. Census Bureau spokeswoman, said to expect to spend 10 minutes answering questions about the first person on the form, and about five minutes for each additional person in the household.

How do I get help filling out the form?

Whoever owns or rents the residence should fill out the form for everyone in the household. Another household member who is at least 15 years old can fill it out.

If you need more help, the form is available in seven languages, with assistance guides in 59 languages. These and other resources are available online at http://2010.census.gov/2010census/. For help by phone, call toll free 866-872-6868, or, in Spanish, 866-928-2010.

Workers will staff 51 "questionnaire assistance centers" in Western Virginia, including 10 to 12 in the Roanoke area. Banners will be posted outside the centers, and the word is being spread to hard-to-count populations here and in other areas where response has been low in the past.

What if I live in a college dorm, nursing home or jail?

People are counted where they are, even if it's a residence you think temporary. So, college students are counted at school. It's the same with nursing home residents and jail inmates. These kinds of residences are treated as "group quarters" by the census, which works with administrators to develop a plan to count people in those quarters.

When do I have to return the form?

There's no exact deadline. The census bureau asks that you return it as soon as possible, ideally by April 1.

Will anyone come to my house?

Yes, maybe five or six times. The census bureau really wants you to fill out and return the form. So, if you haven't done so by late April, expect a knock from one of 1,600 enumerators hired for our part of Virginia.

If that happens, be sure it's a real census bureau worker. You aren't obligated to let the worker in. And the worker shouldn't ask for information such as your Social Security number or bank account number. Real census workers have a badge that displays a phone number you can call on the spot to confirm the worker's identity.

Can I just skip it?

Federal law allows for fines up to $100 for refusal to answer census questions, and $500 for providing false information, though McGee was unaware of any actual prosecutions.

"We like to say it's part of the democratic process and a privilege," she said. "The census bureau is not in the enforcement business. We prefer education."

If I won't really get in trouble, why should I bother?

Census counts are used to determine representation in Congress, so if your area is undercounted, it will also be underrepresented in government. And there's the money. The federal government distributes $400 billion annually based on census counts. Virginia, Roanoke and other communities put a lot of effort into making sure everyone is counted.

What about my privacy?

Personally identifiable information is completely confidential under federal law, the census bureau assures. It can't be shared with other federal agencies, law enforcement or private businesses, McGee said. And this week, the U.S. attorney general determined that laws protecting the confidentiality of census information trump the Patriot Act.

Is the census bureau still hiring?

Yes. The Roanoke census office expects to be hiring enumerators -- the people who go door-to-door to see that unreturned forms get completed -- through April. To apply, go online to www.2010censusjobs.gov or call 866-861-2010.