|Created: 09 Jul 2014||Modified: 23 Jun 2017||BibTeX Entry||RIS Citation|
At present (v1.0, May 2014), the
ctmixtures model performs the following sampling of the evolving population:
What version 1.0 did not include is:
The following diagram shows how time averaging is integrated into the simulation event stream. Time runs from top (start of simulation) to bottom (end of simulation). Between simulation start time and the start of sampling, the population is evolving from its initial condition to quasi-stationarity. Sampling start time is calculated to occur at a multiple of the expected mixing time, to ensure that the population is at quasi-equilibrium.
In the center of the diagram is an interval, marked with a dotted vertical line, depicting the interval over which we track the survival of traits given (Kandler and Shennan 2013).
Above this fixed interval, we take one sample (of duration 1 tick) to begin the survival analysis, and below the interval, a sample of duration 1 to complete it. This sample is directly comparable to the analysis performed in Kandler and Shennan’s paper (although run with Moran versus Wright-Fisher dynamics).
Expanding away from this interval on both sides are a series of samples taken with greater duration. The first is a sample of duration 25, to start and finish the survival analysis, then 50 ticks, 100, and finally 200 ticks. Each pair of samples measures the trait survival when the samples are necessarily of non-trivial duration (and thus time averaged).
In addition, for the “ending” time averaged sample, I also record raw trait counts, frequencies, and other assemblage statistics, as I do with non-time averaged samples.
Kandler, Anne, and Stephen Shennan. 2013. “A Non-Equilibrium Neutral Model for Analysing Cultural Change.” Journal of Theoretical Biology 330. Elsevier: 18–25.