Imagine that macroeconomic policy is geared towards keeping real GDP growth on trend. Assume this rate of growth is 3 per cent per annum. If labour productivity is growing at 2 per cent per annum and the labour force is growing at 1.5 per cent per annum and the average working week is constant in hours, then this policy regime will result in
Answer: a rising unemployment rate
The answer is Option (a) a rising unemployment rate.
The facts were:
Of-course, the trend rate of real GDP growth doesn't relate to the labour market in any direct way. The late Arthur Okun is famous (among other things) for estimating the relationship that links the percentage deviation in real GDP growth from potential to the percentage change in the unemployment rate - the so-called Okun's Law.
The algebra underlying this law can be manipulated to estimate the evolution of the unemployment rate based on real output forecasts.
From Okun, we can relate the major output and labour-force aggregates to form expectations about changes in the aggregate unemployment rate based on output growth rates. A series of accounting identities underpins Okun's Law and helps us, in part, to understand why unemployment rates have risen.
Take the following output accounting statement:
(1) Y = LP*(1-UR)LH
where Y is real GDP, LP is labour productivity in persons (that is, real output per unit of labour), H is the average number of hours worked per period, UR is the aggregate unemployment rate, and L is the labour-force. So (1-UR) is the employment rate, by definition.
Equation (1) just tells us the obvious - that total output produced in a period is equal to total labour input [(1-UR)LH] times the amount of output each unit of labour input produces (LP).
Using some simple calculus you can convert Equation (1) into an approximate dynamic equation expressing percentage growth rates, which in turn, provides a simple benchmark to estimate, for given labour-force and labour productivity growth rates, the increase in output required to achieve a desired unemployment rate.
Accordingly, with small letters indicating percentage growth rates and assuming that the average number of hours worked per period is more or less constant, we get:
(2) y = lp + (1 - ur) + lf
Re-arranging Equation (2) to express it in a way that allows us to achieve our aim (re-arranging just means taking and adding things to both sides of the equation):
(3) ur = 1 + lp + lf - y
Equation (3) provides the approximate rule of thumb - if the unemployment rate is to remain constant, the rate of real output growth must equal the rate of growth in the labour-force plus the growth rate in labour productivity.
It is an approximate relationship because cyclical movements in labour productivity (changes in hoarding) and the labour-force participation rates can modify the relationships in the short-run. But it provides reasonable estimates of what happens when real output changes.
The sum of labour force and productivity growth rates is referred to as the required real GDP growth rate - required to keep the unemployment rate constant.
Remember that labour productivity growth (real GDP per person employed) reduces the need for labour for a given real GDP growth rate while labour force growth adds workers that have to be accommodated for by the real GDP growth (for a given productivity growth rate).
So in the example, the required real GDP growth rate is 3.5 per cent per annum and if policy only aspires to keep real GDP growth at its trend growth rate of 3 per cent annum, then the output gap that emerges is 0.5 per cent per annum.
The unemployment rate will rise by this much (give or take) and reflects the fact that real output growth is not strong enough to both absorb the new entrants into the labour market and offset the employment losses arising from labour productivity growth.
Please read my blog - What do the IMF growth projections mean? - for more discussion on this point.
The question has practical relevance in Australia at present with the recent statement by the RBA that its was hiking rates further because real GDP growth was nearly back on trend. The fact is that the trend growth rate is below the required growth rate and so the monetary policy stance is really locking in higher than necessary unemployment.