Productivity is commonly defined as a ratio between the volume of output and the volume of inputs. In other words, it measures how efficiently production inputs, such as labour and capital, are being used in an economy to produce a given level of output. Broadly, productivity measures can be classified as single factor productivity measures (relating a measure of output to a single measure of input, e.g. labour productivity) or multifactor productivity measures (relating a measure of output to a bundle of inputs, e.g. multifactor productivity). Productivity is considered a key source of economic growth and competitiveness.