I think that these studies are very flawed, speaking as someone who lives in a 3rd world country… I’ll take a wild guess and say that the main indicator or at least one of the main indicators is the number of incidents where government officials were exposed of doing something illegal or unethical…
If that’s the case they’ll end up with heavily flawed diagrams due to the lack of data and reports coming from these corrupt nations
speaking from life experience now, you can’t tell me that in the US for example, you can crtisize a certain party, and your punishment is going to be some accusations or a lawsuit at worse… But here you’ll be kidnapped and erased from existence ( even if you’re a nobody yes, a simple Facebook post is enough )… And then tell me African countries are not that corrupt compared to a secular nation… I’ll just tell you : give me a break