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Dendro Statistics

Statistical Principles in Dendrochronology 1. Statistical distributions ã ã ã ã Why are we interested in “average” growing conditions over time? Average = SIGNAL. Means we must shoot for an average or mean when we sample. Suggests we also must know the variability about this mean. Which means we must be familiar with statistical distributions, which are defined by mean and variance: ã e.g., the normal distribution, the t-distribution, the zdistribution, the Weibull distribution 1. Statisti

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Statistical Principles in Dendrochronology1. Statistical distributions \u2022Why are we interested in \u201caverage\u201d growing conditions over time? \u2022Average = SIGNAL. Means we must shoot for an average or mean when we sample. \u2022Suggests we also must know the variability about this mean. \u2022Which means we must be familiar with statistical distributions, which are defined by mean and variance: \u2022e.g., the normal distribution, the t-distribution, the z- distribution, the Weibull distribution\u2022population \u2022samples are drawn \u2022uncertainty = sampling error = noise \u2022maximize signal (= average), minimize noise \u2022be aware of sampling bias: examples? \u2022easy access \u2022physical limitations (altitude, health) \u2022low budget \u2022downright laziness! 1. Statistical distributionsãsamples are drawn from a population ãdescriptive statistics are calculated (e.g. mean, median, mode, standard deviation, minimum, maximum, range) ãfrequency distribution is calculated 1. Statistical distributions