First, we have to worry about whether there may have been a change in trend growth, for example, due to a rise in trend productivity growth or a change in the trend in labor force participation. If trend growth has increased, whether because of higher labor force growth or higher productivity growth, then we would observe that rapid growth does not raise utilization rates.
Second, we have to worry about whether NAIRU may be declining or, at least, may be lower than currently estimated. If NAIRU is lower than we expect, then the current unemployment rate is less likely to be associated with excess demand in the labor market and therefore poses less risk of higher inflation. Checks and balances are essential here.