It covered a period when the economy had behaved very differently. It came to the same conclusions. The original study had been very careful about econometric validity. It is possible to do valid work in econometrics. It is also possible to duplicate carefully done work.
Similar problems occur in computer science.
He was trying to do research into what actually causes success in rule-based systems. He ran into serious problems with another research group, which went beyond simply refusing to give data. I think our department would prefer for me not to give any more details. But he concluded that such work was impossible in the particular area with which he was involved. In my opinion, anyone who publishes empirical claims in a scientific journal should be required to give people access to the data needed to replicate it or do further analysis of its model.