Email received September 28th 2011## Bovine TB RBCT data

Hello Mary,

I see that you have received a comment which you have added at the bottom

of your article.

Regarding small sample sizes, this is important because small sample size

gives large statistical error. However both the post where the recent data

has been posted and the review in the link which you give supply confidence

intervals. As sample size reduces, confidence intervals tend to increase

and the size of these intervals gives an indication of statistical error.

Figs 42a and 42b in the review at http://www.bovinetb.info/rbct.php show

these confidence intervals. Judging by their size for data taken in the

adjoining lands where perturbation was most pronounced, these intervals and

hence error are just as large, in fact significantly bigger, than the

intervals in the culling areas where beneficial effects are seen. In fact

these intervals for the most recent data are smaller than the intervals for

data which exhibited the effects of perturbation during the cull. In view

of this I am not sure what the comments regarding small sample size are

referring to. Were they referring to the sample size of data portraying the

detrimental effects of perturbation or the continuing beneficial effects

seen in the proactive areas or perhaps some completely different data?

Regarding what this is about, the only peer reviewed piece of work which I

am aware of, which has been released by the MRC, which specifically looks

at how long beneficial effects last after culling stopped is the paper

titled "The Duration of the Effects of Repeated Widespread Badger Culling

on Cattle Tuberculosis Following the Cessation of Culling" which was

published in Feb 2010. This paper stated under the section titled

"Methodology/Principal Finding" the following

<START OF EXTRACT>

We monitored cattle TB incidence in and around RBCT areas after culling

ended. We found that benefits inside culled areas declined over time, and

were no longer detectable by three years post-culling.

<END OF EXTRACT>

Judging by results which have been posted by the MRC since then, this

statement was grossly misleading. Unfortunately this is a peer-reviewed

piece of work which to many people is carrying a lot more weight and

influence than the subsequent postings which are revealing how inept this

statement was.

Regards,

David.