The fall in the US productivity should not be a surprise

Productivity is generally expressed as ratio of outputs to inputs in the production process. Productivity in the US is reported to fall for the first time in more than three decades. The productivity is measured in GDP per hour, which is actually the labour productivity. A fall in the productivity may not be caused by a lack of investment in innovation, as what Bart van Ark, the Conference Board's chief economist stated; it could be caused by firms' optimism about the future economic performance. In recent years, the US has very strong employment growth while the GDP growth rate is disappointing compared with the employment rate. This shows the output (GDP) grows much slowly than the input (employment) grows. Therefore, people should not be surprised about the fall in productivity. The reason for the firms to employ more people, despite their outputs grow narrowly, is largely because they believe the economy will lift up and the increase in their labour force can help them to take advantage in this coming economic boom.