The research report by Richard L. Holmes from the Laboratory of Tree-Ring Research at the University of Arizona discusses the importance of data quality control in tree-ring measurement series, particularly in non-arid regions where climatic signals are weaker. The report highlights the challenges in crossdating and the need for accurate dating to infer climate information. It reviews several computer programs and methods used for crossdating and measurement, including Fritts' correlation routine, Parker's Shifting Unit Dating Program, and others. However, these methods have limitations, such as requiring a known error-free series or being inefficient for large datasets. A new computer program, COFECHA, is introduced to address these issues. COFECHA uses a cubic spline to filter and transform data, derives a master dating series, and tests individual series against this master series. The program identifies segments with low correlations or statistical outliers, indicating potential errors in dating or measurement. The output is divided into six parts, providing detailed information on the correlation of segments, descriptive statistics, and statistical outliers. The report concludes that COFECHA is an efficient tool for data quality control, helping to confirm correct crossdating and document the accuracy of dendrochronological data sets. The program has been successfully applied in various regions, including California, Argentina, and the southwestern United States.The research report by Richard L. Holmes from the Laboratory of Tree-Ring Research at the University of Arizona discusses the importance of data quality control in tree-ring measurement series, particularly in non-arid regions where climatic signals are weaker. The report highlights the challenges in crossdating and the need for accurate dating to infer climate information. It reviews several computer programs and methods used for crossdating and measurement, including Fritts' correlation routine, Parker's Shifting Unit Dating Program, and others. However, these methods have limitations, such as requiring a known error-free series or being inefficient for large datasets. A new computer program, COFECHA, is introduced to address these issues. COFECHA uses a cubic spline to filter and transform data, derives a master dating series, and tests individual series against this master series. The program identifies segments with low correlations or statistical outliers, indicating potential errors in dating or measurement. The output is divided into six parts, providing detailed information on the correlation of segments, descriptive statistics, and statistical outliers. The report concludes that COFECHA is an efficient tool for data quality control, helping to confirm correct crossdating and document the accuracy of dendrochronological data sets. The program has been successfully applied in various regions, including California, Argentina, and the southwestern United States.