Raj Chetty is best known for extremely labor-intensive studies, with dozens of research assistants assembling and cleaning datasets to answer enormous questions. This approach can answer questions that nobody else can really answer, because no one else has the data. Who else has the tax records of millions of people, linked to their home address over decades.
Who else has the tax records of millions of people, linked to their home address over decades. Archimedes said that with a long enough lever he could move the world; with a detailed enough administrative dataset, one can answer anything. Chetty's work is much deeper than mere regressions, though.
Chetty's work is much deeper than mere regressions, though. Reading his work, what I was most impressed by was its depth. It is often clever, ingenious, and gives insights far beyond simply answering a specific question.