Osborne's dynamic plan

How a technical change in Treasury forecasting could help scrap the 45p tax rate.

At the Treasury Select Committee yesterday, in between being quizzed by MPs angry at the extent of the pre-budget leaks, George Osborne revealed that he was planning to enable the OBR to make greater use of so-called "dynamic scoring" when they prepare their economic forecasts – but only when examining tax plans. It may not sound it, but if he made that change, it would be a huge coup for the right.

Dynamic scoring is the practice of including behavioural changes in economic forecasts. Without it, in a static model, changes to revenue after something like a tax hike are facile to calculate. If VAT at 17.5 per cent takes in (say) £175bn, then VAT at 20 per cent will take in £200bn. Similarly, if you are trying to calculate the effects on government revenues of spending £100m buying new trains for the east coast main line, then you can conclude that it will cost £100m – you buy the new trains, everyone carries on riding the line, and nothing changes.

What a static model says is that people are blind to the effect that government actions have when they are choosing what to do. Clearly, that is untrue. But it is also very easy to calculate, which is why it has stuck around for so long.

Dynamic models include all these changes of behaviour. So when looking at a dynamic model for rail investment, you can take into account the fact that nicer trains will make people more likely to travel, boosting ticket revenue; and when looking at a dynamic model for VAT rises, you bear in mind the fact that as prices rise, people buy fewer things, so that an 11 per cent rise in VAT won't lead to an 11 per cent rise in VAT revenue.

The problem for economists is that dynamic models are a lot harder to calculate. Not only are there far more variables to take into account, but you open yourself up to more avenues of attack from political opponents. The combined effect of all the assumptions you must make means that your conclusions can be deeply flawed if you get too many wrong, and, as the IFS says (pdf), can "[open] the door to large controversies if these guesses are made – or perceived to be made – in a politically biased way." While static models contain assumptions that are obviously false, dynamic models still contain assumptions, which can still be just as false. And unlike static models, we can't know which ones these are until it is too late.

So why does George Osborne want to introduce dynamic scoring into OBR models? Does he believe that the government's economists have uncovered a breakthrough understanding in behavioural responses to government intervention?

A clue can be found in HMRC's report into the 50p tax rate, which found that dropping the rate down to 45p would cost far less than expected, because of expected behavioural changes. Indeed, this sort of dynamic thinking is the cornerstone of the Laffer curve, the economic theory that, past a certain point, increasing tax rates reduces revenues.

What Osborne will be hoping is that allowing the OBR to make its models more dynamic still will strengthen the rationale for scrapping the 45p rate entirely, as well as for cutting corporation tax all the way down to 20p by the end of parliament.

Yet while the OBR will be "informed" by these new dynamic models when it comes to tax policy, they won't be taking account of the same information when examining the justification for government investment, where, far from strengthening Osborne's preferred policy, it would weaken it. If dynamic scoring is indeed implemented in this narrow fashion, Osborne will have scored a stealth victory for future Tory policy.

Money on the mind: A 19th century phrenology chart. Credit: Getty

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

Show Hide image

Can Trident be hacked?

A former defence secretary has warned that Trident is vulnerable to cyber attacks. Is it?

What if, in the event of a destructive nuclear war, the prime minister goes to press the red button and it just doesn't work? 

This was the question raised by Des Browne, a former defence secretary, in an interview witht the Guardian this week. His argument, based on a report from the defence science board of the US Department of Defense, is that the UK's Trident nuclear weapons could be vulnerable to cyberattacks, and therefore rendered useless if hacked. 

Browne called for an "end-to-end" assessment of the system's cybersecurity: 

 The government ... have an obligation to assure parliament that all of the systems of the nuclear deterrent have been assessed end-to-end against cyber attacks to understand possible weak spots and that those weak spots are protected against a high-tier cyber threat. If they are unable to do that then there is no guarantee that we will have a reliable deterrent or the prime minister will be able to use this system when he needs to reach for it.

Is he right? Should we really be worried about Trident's potential cyber weaknesses?

Tangled webs 

The first, crucial thing to note is that Trident is not connected to the "internet" we use every day. Sure, it's connected to the main Ministry of Defence network, but this operates totally independently of the network that you visit Facebook through. In cyber-security terms, this means the network is "air-gapped" - it's isolated from other systems that could be less secure. 

In our minds, Trident is old and needs replacing (the submarines began patrolling in the 1990s), but any strike would be ordered and co-ordinated from Northwood, a military bunker 100m underground which would use the same modern networks as the rest of the MoD. Trident is basically as secure as the rest of the MoD. 

What the MoD said

I asked the Ministry of Defence for a statement on Trident's security, and while it obviously can't offer much information about how it all actually works, a spokesperson confirmed that the system is air-gapped and added: 

We wouldn't comment on the detail of our security arrangements for the nuclear deterrent but we can and do safeguard it from all threats including cyber.

What security experts said

Security experts agree that an air-gapped system tends to be more secure than one connected to the internet. Sean Sullivan, a security adviser at F-secure, told Infosecurity magazine that while some hackers have been able to "jump" air-gaps using code, this would cause "interference" at most and a major attack of this kind is still "a long way off". 

Franklin Miller, a former White House defence policy offer, told the Guardian that the original report cited by Browne was actually formulated in response to suggestions that some US defence networks should be connected to the internet. In that case, it actually represents an argument in favour of the type of air-gapped system used by the MoD. 

So... can it be hacked?

The answer is really that any system could be hacked, but a specialised, independent defence network is very, very unlikely to be. If a successful hack did happen, it would likely affect all aspects of defence, not just Trident. That doesn't mean that every effort shouldn't be made to make sure the MoD is using the most secure system possible, but it also means that scaremongering in the context of other, unrelated cybersecurity scares is a little unjustified. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.