That such methodology may be 'peer reviewed' is not in question, but its content may be lacking, weak, assumed or 'tortured' to fit the model. We quote from our contributer's view on just this type of prediction, and its subsequent conclusions which have been described by some as 'coherent argument' offered by the ISG to support their unequivocal conclusions.
To quote F J Bourne:
'Scientific findings indicate that the rising incidence of disease can be reversed and geographical spread contained, by the rigid application of cattle-based control measures alone.' (ref. his letter to Miliband).
‘The ISG also conclude that rigidly applied control measures targeted at cattle can reverse the rising incidence of disease, and halt its geographical spread……….Having shown that the main approach to cattle TB control should be rigorously targeted to cattle, we hope that the overwhelming scientific evidence we have provided to support this view……..’(ref. the ISG press release of 18th June 2007.)
‘Our modelling work indicates that implementation of cattle control measures outlined in this report are, in the absence of badger culling, likely to reverse the increasing trend in cattle disease incidence that has been a feature in GB for decades. It is also possible that more effective cattle controls will lead to a decline of the disease in badgers, although the timescale for this is likely to be slow.’ (ref. Chairman’s overview, section 12.)
‘ Analysis of a simple mathematical model suggests that rigorously enforced movement testing would halt the epidemic and indeed produce some steady decline in incidence…..’(ref. Recommendations and Conclusions. Section 31.)
The comment continues, emphasising that the above quotes were read before reading the main body of the report. The writer admits surprise at these conclusions, but asserts the report was read with an open mind, the reader ready to be reluctantly convinced. What the reader was not expecting was such a lack of scientific rigour in the arguments. As a full analysis is not possible here, the writer concentrates on the mathematical modelling that seems to be the basis of the ISG’s ‘overwhelming scientific evidence’ as follows:
7.24 The effect of changes cannot be assessed directly from available data but simple mathematical models, combined with the large amount of data now assembled, do allow some very tentative predictions. The infection rate concerns all sources of infection for cattle, local infection for example across farm boundaries, infection from animals bought, in particular but not only, from high incidence areas, and infection from wildlife, especially badgers. All these are important but their relative importance, and that of cattle-to-badger transmission, cannot be estimated directly’ .
"So far, so good. The predictions are tentative, indeed, very tentative, and the relative importance of the most important data is unknown. So what scientific or even logical explanation can there be for the next sentence?"
’In the following calculations we assume all three sources to be roughly equally important.’
"If there is available evidence to show that that assumption is a reasonable one what is it? We know that Bourne does not believe there to be such a thing as a closed herd".
‘People claim to have a closed herd, but they simply do not exist’ (Bovine TB seminar for MPs September 14th 2004).
"There is overwhelming evidence that closed herds do exist, so there is one piece of evidence that he is not taking into account at all". (This site was set up by four owners of such herds, precisely for that reason - ed)
"From section 7.19 there is some discussion of the mathematical model , and towards the end of that section the report says":
7.29 These conclusions are subject to substantial uncertainty and should be taken as broad guidance only.
The comment continues: "That is the conclusion I would expect a reputable scientist to come to. There are too many uncertainties and unknowns, and the model is too simple. Substantial uncertainty is not overwhelming scientific evidence".
Kitching et al say in their paper "The Use and Abuse of Mathematical models": …..Rev.sci.tech.Off.int.Epiz.2006.25910, 000-000)
It is not necessary to be mathematically literate to appreciate that no model will produce the right output, when fed the wrong input. In the future, care should be taken to ensure that lessons are learned – a bad model is like a bad x-ray because it invariably results in erroneous conclusions and a wrong course of action.’
(Incidentally, I would very much recommend reading the whole article. There is much more that is very relevant.)
The writer concludes: "So how can such vague inputs into the ISG model come to such a concrete conclusion as this":
‘Analysis of a simple mathematical model suggests that rigorously enforced movement testing would halt the epidemic and indeed produce some steady decline in incidence…..’(ref. Recommendations and Conclusions. Section 31)
The writer also notes that Christl Donnelly, vice-chairman of the ISG, worked on the mathematical model for FMD, which was the basis of the paper published by Kitching et al and entitled "The Use and Abuse of Mathematical Models".