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.

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Let's face it: supporting Spurs is basically a form of charity

Now, for my biggest donation yet . . .

I gazed in awe at the new stadium, the future home of Spurs, wondering where my treasures will go. It is going to be one of the architectural wonders of the modern world (football stadia division), yet at the same time it seems ancient, archaic, a Roman ruin, very much like an amphitheatre I once saw in Croatia. It’s at the stage in a new construction when you can see all the bones and none of the flesh, with huge tiers soaring up into the sky. You can’t tell if it’s going or coming, a past perfect ruin or a perfect future model.

It has been so annoying at White Hart Lane this past year or so, having to walk round walkways and under awnings and dodge fences and hoardings, losing all sense of direction. Millions of pounds were being poured into what appeared to be a hole in the ground. The new stadium will replace part of one end of the present one, which was built in 1898. It has been hard not to be unaware of what’s going on, continually asking ourselves, as we take our seats: did the earth move for you?

Now, at long last, you can see what will be there, when it emerges from the scaffolding in another year. Awesome, of course. And, har, har, it will hold more people than Arsenal’s new home by 1,000 (61,000, as opposed to the puny Emirates, with only 60,000). At each home game, I am thinking about the future, wondering how my treasures will fare: will they be happy there?

No, I don’t mean Harry Kane, Danny Rose and Kyle Walker – local as well as national treasures. Not many Prem teams these days can boast quite as many English persons in their ranks. I mean my treasures, stuff wot I have been collecting these past 50 years.

About ten years ago, I went to a shareholders’ meeting at White Hart Lane when the embryonic plans for the new stadium were being announced. I stood up when questions were called for and asked the chairman, Daniel Levy, about having a museum in the new stadium. I told him that Man United had made £1m the previous year from their museum. Surely Spurs should make room for one in the brave new mega-stadium – to show off our long and proud history, delight the fans and all those interested in football history and make a few bob.

He mumbled something – fluent enough, as he did go to Cambridge – but gave nothing away, like the PM caught at Prime Minister’s Questions with an unexpected question.

But now it is going to happen. The people who are designing the museum are coming from Manchester to look at my treasures. They asked for a list but I said, “No chance.” I must have 2,000 items of Spurs memorabilia. I could be dead by the time I finish listing them. They’ll have to see them, in the flesh, and then they’ll be free to take away whatever they might consider worth having in the new museum.

I’m awfully kind that way, partly because I have always looked on supporting Spurs as a form of charity. You don’t expect any reward. Nor could you expect a great deal of pleasure, these past few decades, and certainly not the other day at Liverpool when they were shite. But you do want to help them, poor things.

I have been downsizing since my wife died, and since we sold our Loweswater house, and I’m now clearing out some of my treasures. I’ve donated a very rare Wordsworth book to Dove Cottage, five letters from Beatrix Potter to the Armitt Library in Ambleside, and handwritten Beatles lyrics to the British Library. If Beckham and I don’t get a knighthood in the next honours list, I will be spitting.

My Spurs stuff includes programmes going back to 1910, plus recent stuff like the Opus book, that monster publication, about the size of a black cab. Limited editions cost £8,000 a copy in 2007. I got mine free, as I did the introduction and loaned them photographs. I will be glad to get rid of it. It’s blocking the light in my room.

Perhaps, depending on what they want, and they might take nothing, I will ask for a small pourboire in return. Two free tickets in the new stadium. For life. Or longer . . . 

Hunter Davies is a journalist, broadcaster and profilic author perhaps best known for writing about the Beatles. He is an ardent Tottenham fan and writes a regular column on football for the New Statesman.

This article first appeared in the 16 February 2017 issue of the New Statesman, The New Times