A comparison of chronologies from tree rings
Forty-five-year ring width index chronologies were estimated by five mean-value functions applied to 183 ring width series from four similar sites. The effects of autocorrelation on the comparisons among mean-value functions were explored by fitting box-Jenkins models to individual-tree index services prior to pooling (prewhitening), and to the pooled chronologies obtained from the mean-value functions (postwhitening). Among the mean-value functions tested, the principal component scores and the biweight yielded the highest cross correlations between chronologies from different sites, whereas the average, the median, and the median polish did not perform as well. Prewhitening and postwhitending tended to decrease both intersite correlations and correlations between chronologies from different mean-value functions for the same site.