Table 2 Summary statistics calculated from the count of years in the current and previous 3 years in which cells with tree-ring dates are in the MFN.Calculations for cells with dates reflect the MFN status for each subperiod of all cells for which any tree-ring date between A.D. 500 and 1400 is present. Calculations for local cells are based on only those cells with tree-ring dates in a given year or any of the previous 3 years. Period boundaries are as given in the text and in Table 1. x̄ is the mean, σ is the SD, *G*_{1} is an unbiased estimator of skewness, and *G*_{2} is an unbiased estimator of kurtosis. See also Fig. 5.