In the summer of 2024, I worked with Conrad Hackett, Stephanie Kramer, Yunping Tong, Anne Shi, and Dalia Fahmy at Pew Research Center in D.C.. At the time, they were working on a report (now published) which measures change in religious identity for every country in the world. While working with the Pew team, I became interested in changes in surveys and census questionnaires over the past few decades. I was especially interested in how people without religious identities were measured.
After investigating over 60 censuses and hundreds of surveys, I came to the conclusion that changes in measurement have possible resulted in exaggerated reports of the growth in religiously unaffiliated populations.
Conrad and I wrote a paper about this, which is under review at the Journal for the Scientific Study of Religion. For now, it is available for review on SocArXiv.