Roswell survey is valid

AS one of those involved in surveying people's use of Roswell Pits, I feel compelled to respond to the criticisms aired by Les Walton in last week's issue. Neither LCPRE nor Dr Balmford have ever claimed that the pits receive 90,000 visitors per annum.

This number refers to visits, not visitors and as Mr Walton rightly states, individual visitors may make multiple visits.

Counting visitors rather than visits is difficult, and prone to error, so most attractions simply count visits as we did.

Ely Cathedral and Wicken Fen do the same, and the comparisons made between Roswell Pits and these other attractions are on a perfectly valid "apples with apples" basis.

The survey was designed so that such comparisons could be made regardless of weather, bank holidays or other peculiarities of the time that the survey was conducted.

To do this, attendance data for Roswell was compared with attendance on the same days at five nearby sites for which there are reliable annual data.

A simple example illustrates the method. If, for example, we counted 100 people at Roswell, on a day when they counted 200 at Wicken, then the annual figure for Roswell, would be estimated to be half that for Wicken.

The actual method is more sophisticated than this, but I hope the principle is clear.

Mr Walton also seems concerned about the credentials of Dr Balmford, and the other scientists involved. It would be tedious to list the qualifications of those involved: suffice to say that of 25 who took part in the four-day survey (two of them very wet) nearly half had PhDs.

The group includes professional scientists from two universities, the United Nations Environment Programme, the World Bank and the World Conservation Union.

Dr Balmford, in particular, is an expert on assessing the value of nature to people and in setting priorities for conservation. His work regularly appears in the top scientific journals, where it has to pass through a rigorous review process before acceptance.

None of us would use "inaccurate" statistics to justify our point of view.

As Mr Walton points out, there has always been and is still, plenty of room to accommodate conservationists, fisherman and the sailing club on the pits.

Indeed, one of the findings of our survey was that people use the pits for a diverse range of activities, all of which currently co-exist on and around its waters .

Unfortunately most people in each of these groups believe they would lose out to a marina wishing to park dozens of diesel-engine boats on the Pit.

DR IRA COOKE

Back Hill

Ely