I’ve tried to do a study of GERS, but I run into anomalies all the time. It struck me yesterday that I’m approaching it from the wrong end. I treat GERS as an accounting document, when it is anything but. Its purpose is not to say how much money Scotland receives or spends; its purpose is to make a guess about it.

So, that is the problem when we’re talking about the economy of Scotland. There are no accounts to rely on. There are no ledgers we can go to that separates out Scottish things from UK things. Nobody knows where the tax comes from. Inverness or Hull? Have a guess.

“Government Expenditure and Revenue Scotland”, or GERS for short, is not useless, however. It is the closest thing we have to real accounting. Therefore, it is the go to document for both supporters of independence and for opponents of it. Wonks and geeks everywhere will definitively slap the table with their interpretation of GERS.

Unionists will point to the tax raised and revenue spent and declare Scotland unviable as an independent state. Independistas will counter with equally assured argumentation for why it says that we’re the richest country on earth.

Sadly, both sides, consciously or unconsciously, makes all the wrong assumptions about GERS. They see it as an economic document, an accounting document. They are wrong because GERS is nothing more than a statistical analysis, and that makes all the difference for how to treat it. Or as Douglas Fraser at the BBC put it in 2014.

Much of this is based on estimates. How much is spent per Scot by the Ministry of Defence in London? How much on the Foreign Office’s services around the world? We can only make informed guesses, or equalise across the UK. How much income tax is paid by Scots for work in Scotland, when there’s nowhere in your tax form that says where you earned it? How much corporation tax can be attributed by Britain-wide firms to their activities in Scotland? We don’t know. The statisticians have to guess. Only on things like stamp duty or council tax, because these are property based, can you tell precisely how much tax is raised and where.

We don’t know. That’s the key phrase here. An economic and accounting analysis of a wallet lying on a table would say how much money was in the wallet, based on previous records and recollections. A statistical analysis of the wallet would attempt to answer another question: within what bounds of a margin of error is the probability for the wallet having any money in it?

That’s the difference between the two. It gives completely different answers. Statistical analysises gives much less secure answers than accounting ones where all you have to do is to look up a ledger and do the sums for previous years.

This isn’t an attempt to discredit GERS. It’s the best we have for what is a required knowledge. Without it, we’d be even worse off, and would look at Scotland’s economy as a black box. We wouldn’t know anything about it. GERS gives us ONE answer that’s likely within a certain margin of error.

I’m an independista. I want Scotland to become an independent country. That means I have to be extra careful about confirmation biases, and scrutinize myself harder than my opponents. And I have to admit to myself that GERS is a flawed instrument for analysis that only gets us so far. It would be better if we had definite accounting of the Scottish economy — but we don’t.

There is actually a chance that Scotland’s economy is worse than GERS says. That’s the dangers of statistical analysis, that we land in the margin of error. If we do, then we can be much worse off, or we can be much better off. There’s no way to say which one it’s going to be. But probability says, GERS is near the actual numbers, with an unspecified margin of error about the actual figures. See it as a guess with a fuzzy curve at the end.

With that margin of error in mind, there’s no evidence for Scotland actually having a deficit at all. There’s also no evidence to say that it is not double or triple of what GERS suggests. We don’t know. It’s all guesswork.