Does OxCal assume we are inputting1 sigma uncertainties?
Marge Belcastro
Hello there!
We are using a modeled calendar date (the death of a tree) as a razor in our stratigraphic age model. We have input this as a C_Date, but wonder if perhaps we should change to C_Simulate? For C_Simulate would we input the cal BP age or the cal BC/AD age (as we do in C_Date)?
Our main question - in our model, we currently use the mean and 1 sigma for our uncertainty from our D_Sequence model but we are unsure if we should use the value μ and 1 sigma, or the 2 sigma age and uncertainty as an input in the new model? Does OxCal assume we are inputting1 sigma uncertainties?
Our D_Sequence model summary statistics of death of the tree is μ 371, σ 5 cal BC/AD.
Below is the relevant section of our stratigraphic age model code.
Phase (Marsh bottom 5)
{
R_Date("5MB", 2040, 70);
};
Phase (Marsh Top 5)
{
R_Date("5MT_Spruce", 1820, 60);
R_Date("5MT", 1760, 60);
};
// Netarts Bay Earthquake 5 (Wiggle-Match Age Range on Outer Tree
Ring, 1 sigma)
C_Date( "Wiggle-Match Age Range on Outer Tree Ring", 371, 5);
Phase ("Marsh Bottom 4")
{
R_Date("4MB", 1450, 80);
};
Phase ("Marsh Top 4")
Thanks for your help with this,
Marge.
Christopher Ramsey
You can use C_Date or just Date as in:
Date( "Wiggle-Match Age Range on Outer Tree Ring", N(AD(371), 5));
this will assume a date with a central point in the middle of 371 - if you use 371.0 that will be the start of the year 371. The errors in OxCal are always standard uncertainties (one sigma).
Best wishes
Christopher
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