Uncertainty about how the economy really works and about the true value of the parameters together with data quality and timeliness (and, consequently, the robustness of estimates) is an essential constraint that not only affects the central bank, but also the private sector.
There is huge uncertainty about the future behavior of the main domestic variables, especially in relation to (both goods and factors) relative price dynamics and that of the various sectors of the economy. Another important restriction is given by the difficulty in identifying the nature of shocks, especially external shocks.