Badgers in the mainframe? Defra’s monumental TB data errors

Back in January I wrote about Defra’s revelation that the vet agency AHVLA’s new computer had been spewing out fictitious reports overstating the number of Herd’s which had suffered a bovine TB breakdown. In retrospect it’s amazing that Owen Paterson lasted as long as he did at Defra, given the number of stupendous gaffes that happened under his watch.

This year Defra has decided to continue with its Badger Cull, but without those pesky independent scientists taking a critical overview of its scientific merit, methodology and effectiveness. The Badger Trust are in the courts challenging the legality of this decision.

Meanwhile, and with no fanfare at all, Defra has released the latest data on Bovine TB herd breakdowns. Again they have found more errors and again they have altered the numbers for previous months and years.

The first figures for September 2013 showed 5,961 herds had a TB reactor, out of 79,501 herds in Great Britain. After two revisions to remove bad data, the figures now show only 4,123 herds had a reactor. The first number is a whopping 45% overestimate of the (current) real figure.

The first month where things went wrong was January 2012, according to Defra. I imagine that’s roughly when the new IT system was brought on line. Initial figures for that month were 4372, this has now been revised down twice, to 4292. That is a much smaller error, overstating by only 2%.

The largest number of herds with TB breakdowns reported was April 13 with 6132. This had been revised down to 4958, and then again recently to 4816. That’s over 27% overestimated.

What is clear is that the error had been getting bigger, much bigger, as the months went on. Why did nobody spot this? Did they want to believe that herd breakdowns were really going up so quickly, as this was convenient justification for the badger cull?

These are GB figures and will hide even larger errors at the country or regional level. Scotland is officially TB free. Imagine the alarm Scottish beef and dairy farmers felt, to see TB breakdowns increasing to 42 in September 13. This figure has now been revised to 18, less than half. That figure has apparently climbed up to 42 in September 2014 – or has it? Can we expect that figure to be revised again?

It beggars belief that there could even be a 233% margin of error for such a small sample.

In England, where most of the TB reactors are found, the highest initial figure was 4,821 herds in April 13. That has so far been reduced to 3750. That’s an overestimate of 29%. That month is when the number of reactors peaked. The figure is 3383 for May 2014.

June 2014 shows a further reduction (at GB level) to 4041 herds, from 4266 in May.

Only 256 new incidents were recorded across GB in June this year and only 150 herds where TB-free status has been withdrawn. Now for those 150 farmers, this is disastrous news and I do not wish to downplay their sorry and anguish.

But Defra has been very misleading in the way that it has portrayed the data errors in its official statistical reports.

defra TB graph jpeg

This new Defra graph purports to show what a small difference there has been between previously published herd breakdown data and the current corrections.


They have compared the data after the initial correction, with the data from the current correction. This graph ignores the first correction.

Here’s the graph they produced first time round (Feb 14):

Defra TB 1st revision jpeg

See what they’ve done here? Changed the time scale on the graph. First graph shows a large error but only for a short time, relative to the whole time scale. Second graph shows a much smaller error (because they have ignored the first much larger error) but over a longer part of the x axis. Nifty, but not that nifty.

Two things come to mind:

  1. We obviously cannot believe anything Defra stats say about the extent of Bovine TB breakdowns, or the trend in breakdowns.
  2. Defra are trying to cover up their monumental statistical cock-up.
  3. The very data used to justify the Badger Cull is so badly flawed that Natural England must reconsider whether the Cull can be allowed, given the rules that determine its legality.

No doubt if Owen Paterson was still Secretary of State at Defra, he would be blaming the badgers for uploading viruses into the AVHLA computer system. What will the new SoS Liz Truss say? So far, all she has done is peddle the NFU line. Reported in the Guardian

The environment secretary, Liz Truss, insisted the cull was crucial. “We are pursuing a comprehensive strategy supported by leading vets, which includes cattle movement controls, vaccinating badgers in edge areas and culling badgers where the disease is rife. This is vital for the future of our beef and dairy industries, and our nation’s food security.

“At present, we have the highest rates of bovine TB in Europe. Doing nothing is not an option and that is why we are taking a responsible approach to dealing with bovine TB.”

She clearly hasn’t been told by her officials that the data on which they are basing their decisions is completely untrustworthy.

About Miles King

UK conservation professional, writing about nature, politics, life. All views are my own and not my employers. I don't write on behalf of anybody else.
This entry was posted in badgers, bovine TB, Defra and tagged , , , , . Bookmark the permalink.

4 Responses to Badgers in the mainframe? Defra’s monumental TB data errors

  1. Mike says:

    The original case for badger culling was also based on the assumption that 50% of herd breakdowns were attributable to badgers. This figure has since been revised by the scientist who made that estimate (Donnelly) to a meagre 5.7%. This leaves the estimated cattle to cattle infection at 94.3%. Clearly the control of infection between cattle is grossly inadequate leaving DEFRA and the NFU culpable for the high level of disease, not the badgers.

  2. David Dunlop says:

    Hmm. I wonder are the data generation systems in the “parallel universes” of Northern Ireland and Ireland (Republic) more or less trustworthy than that in GB.

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