AFAIK the Economist’s Democracy Index and the Human Development Index use methodologies and statistical methods generally respected by social science.
Ad Fontes is a grift posing as a public interest institution to re-package the horseshoe theory and sell it back to gullible people for $500 memberships while promising institutions greater ad revenue if they play along with the con. It’s another tool of the consent manufacturing industrial complex. Are you even aware of their methodology? It’s a joke.