Double the dates and go for Bayes — impacts of model choice, dating density and quality on chronologies
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Reliable chronologies are essential for most Quaternary studies, but little is known about how age-depth model choice, as well as dating density and quality, affect the precision and accuracy of chronologies. A meta-analysis suggests that most existing late-Quaternary studies contain fewer than one date per millennium, and provide millennial-scale precision at best. We use existing and simulated sediment cores to estimate what dating density and quality are required to obtain accurate chronologies at a desired precision. For many sites, a doubling in dating density would significantly improve chronologies and thus their value for reconstructing and interpreting past environmental changes. Commonly used classical age-depth models stop becoming more precise after a minimum dating density is reached, but the precision of Bayesian age-depth models which take advantage of chronological ordering continues to improve with more dates. Our simulations show that classical age-depth models severely underestimate uncertainty and are inaccurate at low dating densities, and also perform poorly at high dating densities. On the other hand, Bayesian age-depth models provide more realistic precision estimates, including at low to average dating densities, and are much more robust against dating scatter and outliers. Indeed, Bayesian age-depth models outperform classical ones at all tested dating densities, qualities and time-scales. We recommend that chronologies should be produced using Bayesian age-depth models taking into account chronological ordering and based on a minimum of 2 dates per millennium.
Blaauw , M , Christen , J A , Bennett , K D & Reimer , P J 2018 , ' Double the dates and go for Bayes — impacts of model choice, dating density and quality on chronologies ' , Quaternary Science Reviews , vol. 188 , pp. 58-66 . https://doi.org/10.1016/j.quascirev.2018.03.032
Quaternary Science Reviews
© 2018 Elsevier Ltd. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.quascirev.2018.03.032
DescriptionThis work was partly funded by a Banco Santander travel grant to MB. We are also grateful to the Past Earth Network (http://www.pastearth.net/) for writing support (grant number EP/M008363/1).
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