wiles

Last week, I posted on the effect of ex post site selection on the Gulf of Alaska tree ring chronology used in Wilson et al 2016 (from Wiles et al 2014).  An earlier incarnation of this chronology (in D’Arrigo et al 2016) had had a severe divergence problem, a problem that Wiles et al had purported to mitigate. However, their claimed mitigation depended on ex post selection of modern sites that were 800 km away from the original selection.

The bias arising from ex post selection of sites for regional tree ring chronologies has been a long standing issue at Climate Audit, especially in connection with Briffa’s chronologies for Yamal and Polar Urals (see tag.)  I discussed it most recently in connection with the Central Northwest Territories (CNWT) regional chronology of D’Arrigo et al 2006,  in which I showed a remarkable example of ex post selection.