Basic age-modelling

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# Basic age-modelling - PowerPoint PPT Presentation

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 14 C dates and depth info

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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

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()

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