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Message: <blockquote data-quote="CPBell" data-source="post: 2057801" data-attributes="member: 85682">You can ask as many times as you like, but you’ll always get the same answer: I have no strong views one way or the other, I would just like policy to be based on reliable evidence.Just to reiterate the main criticisms I’ve offered for the Newson study:<ul> <li data-xf-list-type="ul">Restriction of analysis to English data minimizes the variance of explanatory variables (change in abundance of predators that increased first in Scotland and Wales, then spread to England) thereby reducing the probability of finding significant effects. </li> <li data-xf-list-type="ul">Deletion of individual terms from a linear model where they refer to explanatory variables that are likely to be highly correlated will inevitably result in a negligible (i.e. usually non-significant) change in model variance because of aliasing among the variables. It’s misleading to claim a lack of evidence for predator effects on this basis. </li> <li data-xf-list-type="ul">The results of regression of predator change against prey change are unpredictable, even where there is a strong causal relationship, and the variable outcome will confound the detection of any underlying relationship.</li> </ul>I’ve offered these criticisms in the spirit of scientific enquiry, and with the aim of creating a dialogue on a constructive approach to the issue of bird declines in relation to farming and predators. However instead of engaging the authors have taken cover, so at the same time the <a href="http://www.rspb.org.uk/community/blogs/markavery/archive/2011/02/07/songbird-survival-has-rod-liddle-issues.aspx" target="_blank">RSPB is touting the Newson study </a>as proof that predators don’t affect songbirds, the authors appear to be tacitly admitting that it’s little more than junk science. Meanwhile, the BTO continues to obstruct the implementation of proven methods for the investigation of predator effects. Politically neutral? Yeah right: and I'm a banana.  <a href="http://www.cpbell.co.uk" target="_blank">http://www.cpbell.co.uk</a><a href="http://www.youtube.com/CultoftheAmateur" target="_blank">http://www.youtube.com/CultoftheAmateur</a></blockquote>

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