Gauge China's growth by derivatives use, not GDP data

Using figures such as purchasing power parity, or PPP, to assess the comparative size of China's economy is a pointless exercise. Instead, the derivatives markets give a more useful indicator of China's growing influence in global finance

In November, China's economy expanded beyond that of the US in terms of purchasing power parity (PPP), according to the International Monetary Fund. The Washington NGO's policy wonks now report that China's economy is worth $17.6 trillion, versus $17.4 for the US, on a PPP basis.

Because China is cheaper than the US, a dollar spent in Chengdu will buy more than a single greenback spent in