Chief Economic Advisor V Anantha Nageswaran, today, said that India should not use a weak exchange rate as a guard against inefficiencies and stressed the need for productivity enhancement and investment in research and development by the corporate, and industrial sectors to compete in the global export market. Explaining the China model, the CEA said China's exchange rate policy was an add-on over and above the productivity gains the producers were bringing to exports. "We have tended to take cover behind weaker exchange rates. That should not continue," said Nageswaran.