Impact Study: How the Impact Newspapers were Selected

The pool from which Impact newspapers were drawn comprises English-language U.S. dailies, publishing at least five days a week, with average circulation of more than 10,000. Specialist newspapers and newspapers with significant national distribution were not included.

To select a group of newspapers from that pool that would be as representative of the industry as possible, researchers at the Readership Institute used a stratified sampling method that took into account seven variables, including competition, circulation, penetration, urbanicity, and market size and potential.

Analysis of the newspaper industry using these variables yielded six strata. The strata reflect size, market and competitive situation. Between 16 and 18 newspapers were then randomly selected from each stratum.

While circulation was only one of the variables used in determining the six strata, people frequently ask about the distribution of circulation sizes in the sample. The chart above shows what the circulation groups look like.