The Richard Dawkins Foundation website highlighted a post by Tobin Grant, a professor of political science at Southern Illinois University whose interest is the sociology of religion, and who writes about it at the site “Corner of Church and State” at the Religion News Service.

Grant’s post reports 61 years of measuring “religiosity” (the degree of religious belief) in the US, using statistics he developed in a 2008 paper (reference and free download below). In that paper, Grant combined 14 indices of religiosity into one, and developed a way to not only present that statistic in a way comparable among years, but to check its reliability. (You can read about the “validation” of his measure, the Aggregate Religiosity Index [ARI] in the paper at the bottom.

The components of the ARI are the indices below; the “correlation in the right column is the correlation of each component of the index with…