Days after Nobel laureate Amartya Sen's criticism of his demonetisation move, Prime Minister Narendra Modi today delivered his sharp riposte: "Hard work is more powerful than Harvard". The dig comes a day after GDP data showed that the overnight ban on the two highest value notes in November did not affect growth rate, rather the figures improved. "On one hand are those (critics of note ban) who talk of what people at Harvard say and on the other hand is a poor man's son who through his hard work is trying to improve the economy," the Prime Minister said, addressing a large gathering.