Correlation Function Analysis
Description
Correlation function analysis can be used to determine the optimal time of year that tree-ring data could be used to reconstruct a specific climate variable (Fritts 1976; Blasing et al. 1984; Cook and Pederson 2011). This tool computes correlations between each tree-ring predictor and climate predictand in Year t and t - 1. Leading and lagging of the predictor data is supported. The results for each tree-ring predictor consist of the correlations, p-values, and 95% confidence levels for each month in Year t and t - 1. Clicking the "Plot..." button will display the monthly correlations in Year t and t - 1 for each predictor. If more than one predictor exists, then the other predictors can be displayed by selecting the specific predictor from the drop-down list next to "Displayed Data".
Input Annual Predictor Data
File
Select the input data to analyze by clicking on "Browse" and navigating to the proper file.
Input Data Format
Year / Data
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99".
Start Row
This input is the row number where the main data to be processed begin in the input file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running Dendro Tools topic.
Number of Variables
Enter the number of variables located in the input file.
Lead / Lag
Check this box to create predictor data with leads and/or lags. Dendro Tools will then activate the lead and lag checkboxes. Check boxes with a minus sign to lead the predictor data (i.e., -1 will move each predictor series back one year so year t is directly compared with year t + 1). Check boxes with a plus sign to lag the predictor data (i.e., +1 will move each predictor series forward one year so year t is directly compared with year t - 1). A checkmark included in the box "0" will tell Dendro Tools to also consider the original predictor data in year t with no lead or lag.
Input Monthly Predictand Data
File
Select the input data to analyze by clicking on "Browse" and navigating to the proper file.
Input Data Format
Year / Month / Data
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99".
Start Row
This input is the row number where the main data to be processed begin in the input file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running Dendro Tools topic.
Output
File
Select or enter the name of the file where the results will be stored.
Header
Information entered here will be output in the first line of the output file.
Parameters
Start Year
Enter the year to start the analysis.
End Year
Enter the year to end the analysis.