The graph is "odd" because it's looking for causality not correlation. If more developed countries are more educated all it proves is that education is a normal good and that people consume more of it as they get richer. That would prove nothing about whether education causes economic growth.
Your point about noisy measurements, such as it is, applies to all macroeconomic measurement. If you're willing to proclaim radical scepticism about all macroeconomics fine. Otherwise this is just an isolated demand for rigour.
The authour is on fact an economist and he references two different economics papers in the post, with links in support of his argument. And of course he has an agenda. Everyone has an agenda. The agenda of the agendaless is continuation of the status quo. Neutrality is an illusion.
Your point about noisy measurements, such as it is, applies to all macroeconomic measurement. If you're willing to proclaim radical scepticism about all macroeconomics fine. Otherwise this is just an isolated demand for rigour.
The authour is on fact an economist and he references two different economics papers in the post, with links in support of his argument. And of course he has an agenda. Everyone has an agenda. The agenda of the agendaless is continuation of the status quo. Neutrality is an illusion.