Saturday, 31 August 2013

Defra Ragwort Code of Practice Nonsense

Defra's ragwort Code of Practice is widely quoted and cited, but it is really often quite an unscientific document.
Today I am celebrating a little as this blog has been running for several years now and every August it gets the highest number of hits as ragwort hysteria is at its height and every August it does better than the one before. This year however it broke the record for the highest number of hits in a month some weeks ago and yesterday it passed the point of double the hits of last August. So today I thought it would be appropriate to tell everyone just how incompetent Defra have been. They have been very incompetent.

First let's look at one of the methods they use to estimate the risk to horses . To quote them:-

A figure of 500 horse deaths from ragwort poisoning in 2000. This figure is based on the number of confirmed horse deaths from ragwort poisoning seen by the Philip Leverhulme Large Animal Hospital Teaching Hospital at Liverpool University as a percentage of all the horse cases treated during the year, and grossed up to be representative of the total horse population.
I can hear the gasps from those of you with training in statistics! They did what!!?

You can't do this and get a sensible answer. Cases in a hospital,. whether of people or of animals, are not a representative sample of what is the case for the country as a whole. They are all concentrated in one place, so you cannot extrapolate and get a meaningful answer. Imagine, if you like, an opinion poll on political beliefs asked just people  in one of the party headquarters and then  extrapolated to the whole country. Do you think it would give a proper accurate answer?

Dr Ben Goldacre (a medical doctor and journalist) is well known for his work on educating people about Bad Science , both through his book of that name and his similarly named column in the Guardian  newspaper. In one of his articles he makes a very relevant comment which seems entirely pertinent to this situation.

We can't do a full census of the whole population every time we want some data, because they're too expensive and time-consuming. Instead, we take what we hope is a representative sample.
This can fail in two interesting ways. Firstly, a sample can be systematically unrepresentative: if you want to know about the health of the population as a whole, but you survey people in a GP's waiting room, then you're an idiot.

You can actually do a GCSE in statistics. ( For foreigners this is the General Certificate in Secondary Education that school pupils usually do at 16.)
These are the assessment objectives:-

AO1 Analyse a statistical problem and plan an appropriate strategy
AO2 Describe and use appropriate methods to select and collect data
AO3 Process, analyse and present data appropriately
AO4 Use statistical evidence to identify inferences, make deductions and draw conclusions
Ask yourself, do you think Defra would pass?

What is more while we don't actually know how many cases of ragwort poisoning the Phillip Leverhume Hospital recorded in 2004 when the Code of Practice was published., thanks to the Freedom of Information Act I can tell you how many they recorded in 2006. In fact I have their figures for 2006-2010, a full five years. They didn't record a single case in the whole five year period! 

It is also worth noting that the tests used would not have been definitive anyway since no test for ragwort poisoning that is definitive exists. The changes in the liver cannot be distinguished from other causes such as those caused by toxins produced in mouldy feedstuffs. See Ragwort Poisoning test.

Then we have Defra distances for where ragwort should be controlled in the vicinity of grazing land. They bear no resemblance to the studies on seed dispersal. We are told there is a risk at 100m when the seeds have been shown not to normally travel more than about 37 metres. Taken with the bizarre overestimation of poisoning risk this is totally unreasonable.

The whole idea that fresh ragwort is a  significant danger to livestock is completely without foundation and contrary to one of the most basic tenets of biology. As I keep saying, animals have co-evolved with the plants with the ragwort toxins which are actually 3% of the plants in the world. Those that ate poison died and did not pass on their genes. We find when we look at the research that animals have a whole set of resistance systems one of which is a complex system of taste genes and receptors which means they know what is good to eat.

This of course makes complete sense. The man who discovered this is so venerated in the UK that if you were to stop the average person in the street you would find they were carrying his picture in their wallet.
Charles Darwin is featured on the Bank of England Ten Pound Note!

The only problem is when owners abuse their animals by feeding it  in quantities in hay or where animals are cruelly abused by starvation. Just remember here that when you throw out the nonsensical claims of poisoning figures derived by measures that would not apparently get you a pass grade in a GCSE exam, and you exclude the abuse cases, ragwort is not a problem at all. Poisoning even including the abuse is actually very rare.

Then of course there is the damage to the environment, as Buglife put it recently in discussing the New Forest
( Again for non-UK people an ancient royal hunting ground  that was "New" when it was created by the man who became king in 1066.)
Ragwort within dried hay is known to cause illness in horses and hay-growers have a duty to remove it from their hay crop. But horses and ponies will not eat it as a live plant within open heathland and pasture. Indeed, ragwort and New Forest ponies have co-existed happily for centuries with no recorded cases of ragwort poisoning.
Absolutely and their expert Steven Falk said

"Ragwort pulling in the New Forest is a truly ill-informed and damaging activity that is totally unnecessary. There are so many rare insects in the Forest, and it is well known that a general reduction in the number of flowers in the Forest over recent decades has placed many insects under severe threat of extinction there. Examine any patch of flowering ragwort in fine weather and you will see an astonishing array of bees, butterflies, hoverflies and beetles".
Finally we come to a spectacular example of poor  critical thinking skills in Defra's guidance

A particular concern amongst conservation groups is that the public pressure surrounding the Code will compel land managers to carry out more extensive control measures than they would otherwise...........

There are concerns that the risks presented by ragwort on grazed nature conservation grasslands could lead to major changes in grazing regimes. These could conceivably include the abandonment of grazing on grassland and heathland sites, leading to the development of scrub and woodland which may have a consequential significant effect on biodiversity.
22 However, as has already been stressed it is not the intention of the Code of Practice to affect the balance of biodiversity. It should be remembered that the control of ragwort has been required long before the introduction of the Weeds Act 1959, which consolidates earlier legislation dating from 1921, without resulting in such drastic consequences
It is really hard to find a calm form of words  to describe what at best is seriously cognitively deficient misinformation and in reality seems more like egregious dissembling.

It doesn't matter what the "intention" is, it is the effect. In fact it is agricultural intensification pushed by people like Defra that has led to the massive declines in wildlife in the UK. Furthermore they know that ragwort control, which is NOT  automatically required by the legislation as they try to imply, was never pushed before the current hysteria. It also sounds rather like an argument from tradition which should lose any students marks in a science essay as it is a well-known example of a logical fallacy

 I want to reuse this blog post  You frequently encounter people on-line who say things like Defra are experts what do they say , or you should listen to Defra they  are part of the government they must be right. This is an answer to the people who say that.

 This is another one of those logical fallacies it is called "argument from authority". It is a falsehood. Just because someone is in a position of authority doesn't mean they are right. In this case Defra have made a real hash of some of their science.

Indeed, we know from very good, basic and fundamental research into the nature of personality that those who argue from tradition and authority and who are concerned that people have a responsibility to follow government advice tend very clearly to be less intelligent and we do see such examples out in the world of the ragwort basher.

And really finally a little joke. There is a word in Welsh. It is spelled with two Fs but the sound is the same. "Deffra". It is a command. It means "Wake up!". I think they should!

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