Years ago, someone said trying to manage a modern economy is a bit like trying to drive the car when both the front and rear windows are covered over.
It is not only the future which is very uncertain but we cannot even be sure about what has happened in the recent past.
The point is that statistics about recent performance of the economy are often either non-existent or very unreliable. They are liable to revision.
Given this, the confidence in some part of the media, notably the BBC and The Financial Times, that Northern Ireland is growing more rapidly than the rest of the UK, and that this difference is down to the protocol is misplaced.
Some reference is made to modelling or estimation on behalf of the Office for National Statistics (ONS) of regional growth across the UK through to September 2021 but what was not adequately reflected was that the ONS estimates show Northern Ireland grew less quickly than the UK average during April to September 2021.
The Financial Times made much play of indications that the volume of output in Northern Ireland has more or less got back to where it was end of 2019 (ie, a return to pre-Covid).
Such claims probably rely strongly on comparing one data source for Northern Ireland, the Composite Economic Index, with a different type of data for Great Britain: Gross Domestic Product (GDP).
The Northern Ireland Statistics & Research Agency (Nisra) would be very open about saying the Composite Index is not directly comparable to GDP and comparisons should therefore be made cautiously.
It is doubtful that Northern Ireland output has got back to pre-Covid. Non-food retail and aerospace (both badly hit by pandemic) are proportionally larger here.
The Composite Index, unlike the GDP data for GB, measures the output of the Northern Ireland public sector by a straightforward count of employment.
Given the Covid boost to public sector jobs that may give an unduly optimistic view of what was really happening to output growth, especially relative to GB.
And, finally, the Financial Times make the leap that IF performance is better than Great Britain this must be because of the protocol: an “after this because of this” logical fallacy.
There are some market access advantages from the protocol, selling to Republic of Ireland plus rest EU, but it may still be the case that increased costs on the much greater volume of east-west trade (ie the £10bn of goods and raw materials brought in from Great Britain each year) will outweigh such north-south gains.
Certainly, the data/estimates given some prominence in the media on Tuesday do not allow us to definitively say what is the overall impact the protocol.