To create this news application, NPR StateImpact obtained data from the Idaho Department of Labor. It’s the state agency responsible for gathering and tracking workforce and employment trends in Idaho. StateImpact acquired monthly seasonally adjusted unemployment data from January 2005 through December 2011 (the latest data available at the county level).

Seasonally adjusted unemployment tracking is a statistical technique which eliminates the influences of holidays, weather, the opening and closing of public schools and other recurring seasonal events. This allows economists to get a clearer picture of the state’s employment trends. It is easier to compare data from month to month using seasonally adjusted data. Non-seasonally adjusted data is helpful for looking at trends over time.

While the Idaho Department of Labor tracks the number of people who are unemployed, it has a harder time tracking the number of people who are underemployed or who have stopped looking for work. The department releases these estimates on an annual basis rather than monthly. So, the term “workforce” refers to the number of Idahoans who are actively looking for a job.