The announcement of the relaxation of China's one child policy created great discussion in China and internationally. But its significance was widely misunderstood. Contrary to myth, the increase in China's labor supply plays little role in China's rapid economic growth. In reality, 96 percent of China's economic growth comes from factors other than a rising labour supply. Therefore, there is no reason why China's economy should slow significantly because China's working age population stopped growing in 2012. The mistaken view, sometimes expressed, that China will grow old before it becomes rich is therefore the reverse of the reality: China will grow rich before it grows old. To demonstrate clearly why, first the facts will be stated and then their implications analysed.

A worker of a company processes galvanized products in Qingdao, east China's Shandong Province, Nov. 1, 2012. [Xinhua/Yu Fangping]

Even an elementary back of an envelope calculation shows why increases in China's working age population have made only a relatively small contribution to China's economic growth. Indeed, this is so immediately clear it is somewhat of a puzzle that the myth ever existed in some quarters that China's growth depended essentially on increases in labor and therefore China's economic growth faces a serious "demographic challenge" due to the end of the increase in the working age population.

From the beginning of reform in 1978 up to 2012, the average annual increase in China's population aged 15-64, the international definition of working age, was 1.7 percent. Over the same period the annual average increase in China's GDP was 10.2 percent -- almost six times as fast. The increase in China's working age population was therefore only 17 percent of the rate of increase of China's GDP -- showing clearly that the rate of growth of population could not possibly explain, or be the main reason for, China's rapid economic growth.

Looking at the trends in more detail shows still more clearly that population trends did not determine China's economic trajectory. Taking five year moving averages for changes in working age population and GDP, to remove the effects of short term fluctuations, China's average annual growth rate of working age population was 2.8 percent in 1983, five years after the beginning of reform. By 2000 this had fallen to 1.6 percent, and by 2012 it was only 0.6 percent. The growth rate of China's working age population was therefore consistently falling.

But China's GDP growth showed the exact opposite trend. Annual average GDP growth rate was 8.1 percent in 1983, 8.6 percent by 2000, and 9.3 percent by 2012. Therefore while the growth rate of China's population was falling its economy was accelerating! This shows clearly changes in China's labor supply were not the prime cause of its economic growth.

Making exact calculations shows the situation even more graphically. It might be naively imagined that as China's working age population grew at 17 percent of the rate of its GDP increase therefore increases in labour accounted for 17 percent, which is under one fifth, of the increase in China's economic growth. This contribution would already seem surprisingly small for those who believe increases in working age population was a major factor in China's economic development, that China's growth rate must therefore now necessarily fall sharply, and China will "grow old before it grows rich." But in reality even 17 percent is a great exaggeration of how much increase in the labor supply contributed to China's growth.

The reason for this is that the increase in the amount of time actually worked grows more slowly than the increase in the working age population. This is because the period of time spent in education rather than work tends to increase, vacations tend to get longer reducing the number of days worked, and other factors.