The best test of whether a covariate is related to the primary variate – a prerequisite for cokriging – is to perform a regression analysis. In GS+ the results of the regression of the primary variate Z vs. the Covariate Z2 is presented in the Data Summary Regression tab. Clicking the Enlarge command in that window brings up the Cross-Variate Regression window:
You may Print, Copy, Edit, Export, or List graph values for either graph using the menu commands of the main GS+ window, or via a right-click menu.