ONS decides to continue with inaccurate RPI calculation

Statistics agency chooses consistency over accuracy.

Against expectations and the recommendations of a number of influential economists, as well as its own consumer prices advisory committee, the ONS has decided not to change how the RPI – one of the two key indices measuring the rate of price inflation – is calculated.

The pressure to examine the index comes from the longstanding difference between the RPI and CPI measures of inflation. Except for the brief period in the midst of the recession, when both indices were recording deflation, RPI has consistently shown levels of inflation higher than CPI. Here's the chart for the last three years, for instance:

 

Some of that difference is due to the fact that the two indices measure subtly different things – RPI includes a broader measure of housing costs, for instance, and it ignores very high and low income households. But the ONS has known for a while that there is also a discrepancy caused by the different formulae used to calculate them.

The ONS began a consultation into whether and how it should eliminate this "formula effect", and has concluded that:

Use of the arithmetic formulation (known as the ‘Carli’ index formula) in the RPI is the primary source of the formula effect difference between the RPI and the CPI… This formulation does not meet current international standards.

So what's it going to do about it? Well, nothing:

The National Statistician also noted that there is significant value to users in maintaining the continuity of the existing RPI’s long time series without major change, so that it may continue to be used for long-term indexation and for index-linked gilts and bonds in accordance with user expectations.

Therefore, while the arithmetic formulation would not be chosen were ONS constructing a new price index, the National Statistician recommended that the formulae used at the elementary aggregate level in the RPI should remain unchanged.

The ONS will, however, develop a new measure of inflation, called RPIJ, which will use a different, better, mathematical formula.

The consumer prices advisory committee, a body which meets around five times a year to advise the ONS on measures of inflation, accepted that the ONS has a responsibility to make sure that there is a level of continuity in the RPI calculations which would be destroyed if there were a change to the formula. But, given the ONS also has a responsibility to compile those statistics "in line with best practice", CPAC concluded that not changing RPI would be "unsuitable".

On the other side, arguing for no change, were 332 of the 406 replies to the public consultation. The ONS said:

The large majority of responses did not address methodological issues but identified the impact that the changes implied… would have for them.

The competing requirements present a tricky path for the ONS to follow, but it does feel like it has picked the wrong option at this point. The job of the statistics agency is surely to produce accurate statistics, rather than statistics which are continually inaccurate in known ways. The fact that RPI is used to decide the value of, amongst other things, index-linked bonds is a reason for it to be correct, not for it to be artificially inflated.

As it stands, the ONS has decided to continue publishing a "measure" of inflation which has an accepted and understood upward bias of 1 per cent a year. It has done this, not because of any real statistical reasoning, but because greater accuracy would be bad for a majority of stakeholders. That seems like a bizarre abdication of its duty.

Photograph: Getty Images

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

GETTY
Show Hide image

Cabinet audit: what does the appointment of Andrea Leadsom as Environment Secretary mean for policy?

The political and policy-based implications of the new Secretary of State for Environment, Food and Rural Affairs.

A little over a week into Andrea Leadsom’s new role as Secretary of State for Environment, Food and Rural Affairs (Defra), and senior industry figures are already questioning her credentials. A growing list of campaigners have called for her resignation, and even the Cabinet Office implied that her department's responsibilities will be downgraded.

So far, so bad.

The appointment would appear to be something of a consolation prize, coming just days after Leadsom pulled out of the Conservative leadership race and allowed Theresa May to enter No 10 unopposed.

Yet while Leadsom may have been able to twist the truth on her CV in the City, no amount of tampering will improve the agriculture-related side to her record: one barely exists. In fact, recent statements made on the subject have only added to her reputation for vacuous opinion: “It would make so much more sense if those with the big fields do the sheep, and those with the hill farms do the butterflies,” she told an audience assembled for a referendum debate. No matter the livelihoods of thousands of the UK’s hilltop sheep farmers, then? No need for butterflies outside of national parks?

Normally such a lack of experience is unsurprising. The department has gained a reputation as something of a ministerial backwater; a useful place to send problematic colleagues for some sobering time-out.

But these are not normal times.

As Brexit negotiations unfold, Defra will be central to establishing new, domestic policies for UK food and farming; sectors worth around £108bn to the economy and responsible for employing one in eight of the population.

In this context, Leadsom’s appointment seems, at best, a misguided attempt to make the architects of Brexit either live up to their promises or be seen to fail in the attempt.

At worst, May might actually think she is a good fit for the job. Leadsom’s one, water-tight credential – her commitment to opposing restraints on industry – certainly has its upsides for a Prime Minister in need of an alternative to the EU’s Common Agricultural Policy (CAP); a policy responsible for around 40 per cent the entire EU budget.

Why not leave such a daunting task in the hands of someone with an instinct for “abolishing” subsidies  thus freeing up money to spend elsewhere?

As with most things to do with the EU, CAP has some major cons and some equally compelling pros. Take the fact that 80 per cent of CAP aid is paid out to the richest 25 per cent of farmers (most of whom are either landed gentry or vast, industrialised, mega-farmers). But then offset this against the provision of vital lifelines for some of the UK’s most conscientious, local and insecure of food producers.

The NFU told the New Statesman that there are many issues in need of urgent attention; from an improved Basic Payment Scheme, to guarantees for agri-environment funding, and a commitment to the 25-year TB eradication strategy. But that they also hope, above all, “that Mrs Leadsom will champion British food and farming. Our industry has a great story to tell”.

The construction of a new domestic agricultural policy is a once-in-a-generation opportunity for Britain to truly decide where its priorities for food and environment lie, as well as to which kind of farmers (as well as which countries) it wants to delegate their delivery.

In the context of so much uncertainty and such great opportunity, Leadsom has a tough job ahead of her. And no amount of “speaking as a mother” will change that.

India Bourke is the New Statesman's editorial assistant.