They assumed a minimum correlation of 0.3, whereas sites in the 15th century MBH98 tree ring network has an average correlation to gridcell temperature of -0.08 (with relative strong average correlation to precipitation.) (realclimate.org)
(Note that empirical AR1 coefficients place less structure on the autocorrelation than the hosking.sim simulations used with the NOAMER tree ring network in our 2005 simulations and simplify this aspect of this analysis.) (climateaudit.org)
In fact, the Corrigendum did not even mention the use of «stepwise» principal components calculation of tree ring network principal components, a matter which was not mentioned in MBH98 and which later formed much of the content of the new SI. (uoguelph.ca)