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Using simulations and data to evaluate mean sensitivity (ζ) as a useful statistic in dendrochronology


Andrew G. Bunn
Esther Jansma
Mikko Korpela



Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Pacific Southwest Research Station


Dendrochronologia 31(3): 250-254


Mean sensitivity (ζ) continues to be used in dendrochronology despite a literature that shows it to be of questionable value in describing the properties of a time series. We simulate first-order autoregressive models with known parameters and show that ζ is a function of variance and autocorrelation of a time series. We then use 500 random tree-ring data sets with unknown parameters and show that ζ is at best equivalent to the standard deviation of a time series in cases without high autocorrelation and is an inefficient estimator of the coefficient of variation. It is hard to justify the use of ζ as a useful, descriptive statistic in dendrochronology on theoretical or empirical grounds. It is better to make a thorough evaluation of the time series properties of a data set and we suggest various avenues for doing so including some that are maybe unfamiliar to most dendrochronologists including generalized autoregressive conditional heteroscedasticity (GARCH) models.


Bunn, Andrew G.; Jansma, Esther; Korpela, Mikko; Westfall, Robert D.;Baldwin, James. 2013. Using simulations and data to evaluate mean sensitivity (ζ) as a useful statistic in dendrochronology. Dendrochronologia 31(3): 250-254. doi:


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