Basic age-modelling
Find ages for dated and undated depths E.g., linear interpolation, regression, spline (gaps) Choose which one looks nicest... How treat point estimates? (mid/max, multimodal)
Bayesian age-modelling
Bayesian = combine data with other info 14C dates and depth info stratigraphical ordering / position
• e.g., wiggle-match dating Constraints on e.g. likely accumulation rates Other dates, e.g. pollen events, 210Pb (…) Outlier analysis
Usually done by millions of simulations
Wiggle-match dating
Outlier analysis
• Reasons: site, error, lab?• Give prior outlier probabilities to dates• Iteration i: is date within 2 lengths sd?• If not, label date and shift to fit• [Labelled / total] posterior outlier
prob.• No need to remove outliers!• Fit F: 1 – mean(posterior outlier prob.)
OxCal
• Extract OxCal directory to C:\Program Files
• Open .../OxCal/Index.html in Firefox
• R_Date( “test”, 2450, 50);
• Save file, run
• Run examples from manual
Bpeat
• Extract Bpeat.zip somewhere
• Open R there (or change dir)
• source(“Bpeat.R”)
• SetCore(“MSB2K”,2)
• TestRun()
• FinalRun( 0.1 ) # just a short run...
• DepthChron()
The future of Bpeat: Bacon
Bacon
Muscles and fat – robust, yet flexible Floppy/crusty – flexibility can be adapted Can be cut to your liking – hiatuses Cured – Bpeat bugs repaired MacBacon – multi-platform Pigs are smart – combine prior info + new
data Pigs can fly – workshop in Mexico
Age-modelling … your own data?
Try the different software pieces What are best settings for your site? Do you agree with the age estimates? Differences between approaches
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