And just as with inflation, our understanding of the labour market can always be improved as we are faced with new data, new developments, and as new research methods become available. That said, there are widely-recognised limits to what monetary policy can do over the long run.
We have some influence over the degree to which the unemployment rate, as just one example, deviates from its underlying trend. But ultimately that underlying trend is determined by factors outside of our ability to influence, that rely instead upon the age and skills of the population, the efficiency with which jobs are matched to available workers, and the nature of employment regulation.