For every set of facts that helps us grasp an important issue, critical data gaps can abound. Surfacing what is not known can matter as much as tracking what is - a key tenet of the State of the USA's editorial approach.

Consider, for example, grandma's living arrangements.

The Federal Interagency Forum on Aging-Related Statistics is an organization of officials from 15 federal agencies concerned with the needs of older Americans and their families. In a 2008 report, the forum examined 38 key indicators -- known sets of facts that forum members say offer a portrait of the nation's seniors. Those measures were divided into five subject areas: population, economics, health status, health risks and behaviors, and health care.

In addition, the forum explicitly called out several areas as targets for needed data development. Among the insufficiently understood: the day-to-day living arrangements for rapidly growing numbers of the nation's elderly.

Much is measured and understood about traditional home care and nursing homes. However, experts in aging readily admit not so much is known about assisted living centers, group housing, residential care retirement communities and the like - facilities that are home to what those experts describe as a significant and fast-growing percentage of the nation's seniors. Meanwhile, the number of people in the United States who need long-term care is expected to increase to 27 million by 2050, twice the long-term care population of the year 2000, according to the National Center for Health Statistics, part of the interagency forum.

What is "known" about the community settings of Americans over age 65 today, then, may not account for the actual experiences of a sizable and increasing proportion of them. The result: care consumers, family members, policymakers and providers can be at a loss to assess individual communities based on national evidence. How well do residents function from one setting to the next? What service-level differences exist based on size or geographic region? What is the range of services offered? A significant data gap affecting potentially millions of families across the country had been identified,

In response, the U.S. Department of Health and Human Services this year is launching the first-ever National Survey of Residential Care Facilities. Approximately 2,250 facilities will participate, selected at random. Information to be collected includes: facility statistics such as size, ownership, staffing and certification status; resident demographics, health status and activity levels; and resident services and charges.

"This study will provide for the first time a national picture of assisted living and residential care communities, the characteristics of the people who live in them, and the range of services received by residents," according to a CDC Q&A for survey participants. "These data will help characterize how residential care and assisted living communities meet the needs of elders and adults with disabilities and help shape future long-term care policies."

Information gaps can come to light when statisticians are asked to supply data for an important policy question not yet answered with hard facts. In other words, someone somewhere is faced with making decisions in a vacuum when the preference - one might hope - is a recommendation based on actual evidence.

Katherine Wallman, chief statistician at the Office of Management and Budget (and government observer on the State of the USA National Advisory Group) put it this way in her forward to the 2008 report: "By displaying what we do and do not know, this report challenges federal statistical agencies to do even better."

The State of the USA approach shares that goal. For more on identifying and reporting data gaps, see the editorial policy in our About section.

Howard Parnell is editor and vice president of content and creative for State of the USA.