Computer Assisted, Independent Observer Verification of Tree-Ring Measurements

Abstract

The importance of tree-ring analyses to forestry and other disciplines (e.g., climate and ecology) requires that tree-ring measurements be as accurate as possible. Accuracy of tree-ring measurement, although often emphasized, may not be stressed as much as other areas of the research. Nonetheless, poor quality measurement data compromise the reliability of interpretations. Possible errors include individual ring mismeasurement errors, consecutive ring errors, multiple ring misdating errors, and multiple ring systematic errors. Verification of measurements can be accomplished by an independent observer who remeasures certain segments from randomly selected cores or cross sections and then uses the computer program VERIFY5 to quantitatively and qualitatively compare both sets of measurements. This program features analyses-such as comparative statistics, least squares analysis, and outlier detection-that can isolate specific measurement errors. Such errors can be minimized by: (1) proper training in the hardware and software used; (2) training in certain rudimentary dendrochronological skills; (3) developing a deliberate measuring pace; (4) consistently using VERIFY5 by an independent observer; (5) using a quality control program (such as COFECHA) to further check measurements and crossdating.