Combining Dates to reduce Standard Deviation

[Johnny Dodge]

Hi all, sorry in advance if this is explicitly answered somewhere else, I've been messing with this for a few days and haven't figured it out yet. 

I have 9 radiocarbon dates from different archaeological samples, which we feel good about sorting into 3 phases--an early phase, a middle phase, and a later phase. When I code it in that way, it doesn't cause any problems in the program, but date ranges are a bit broader than we might like them to be. We are considering combining those dates, in the phases, hoping that would reduce the standard deviation and improve the output. 

My first question, is this a valid step to take, or are there problems to consider with getting cute with the code like this?

My next question, would it be better to use the Sum, the Combine, or a different command altogether to do this? Alongside this question, do I keep the Phases, and have the combined dates in their three phases, or do the new commands act as a phase and make that redundant?

Thanks for any help, I'm attaching my code here 

Johnny

Plot()
 {
  Sequence()
  {
   Boundary("Start");
   Phase("Early")
   {
    R_Date("TR",1020,30);
    R_Date("TF1",1020,60);
    R_Date("TF2",960,60);
    R_Date("RR",1150,25);
   };
   Boundary("transition 1");
   Phase("Middle")
   {
    R_Date("SP2",850,30);
    R_Date("SP1",900,30);
    R_Date("SPA",910,115);
   };
   Boundary("Transition 2");
   Phase("Late")
   {
    R_Date("EL60",935,110);
    R_Date("BM",970,150);
   };
   Boundary("End ");
  };
 };

[Thomas S. Dye]

Aloha Johnny,

Johnny Dodge <jdo...@email.sc.edu> writes:

> I have 9 radiocarbon dates from different archaeological
> samples, which we feel good about sorting into 3
> phases--an early phase, a middle phase, and a later phase. When
> I code it in that way, it doesn't cause any
> problems in the program, but date ranges are a bit broader than
> we might like them to be. We are considering
> combining those dates, in the phases, hoping that would reduce
> the standard deviation and improve the output.

Why do you feel good about the 3 phases, when the age
determinations for the late phase are all older than those for the
middle phase? This seems like a good reason to feel bad about
them.

I'm not sure which date ranges are broader than you might like
them to be.

Nevertheless, it might be useful to experiment with a two phase
sequence, where the early phase is identical to your early phase
and the late phase comprises the five age determinations from your
current middle and late phases. Perhaps this will yield date
ranges that meet your needs.

hth,
Tom

--
Thomas S. Dye
https://tsdye.online/tsdye

[Johnny Dodge]

Great points Thomas! We were basing the phases on some stratigraphic info, but it's not perfect stratigraphic info so you are probably correct that the ranges in the dates themselves don't give much confidence to that. I appreciate the perspective, we'll give it a try with just two phases.

Best,

Johnny