std.paleoTS {paleoTS} | R Documentation |
This function standardizes a paleoTS
object, converting the data to within-populations standard deviation units.
std.paleoTS(y, zero = "start")
y |
a paleontological time series |
zero |
if zero = "start" , trait values are translated such that the initial starting value of the sequence is set to be zero. All other values are ignored. |
The standardization expresses each sample mean as the deviation from the overall mean, divided by the pooled within-sample variance. Sample variances are also divided by the pooled sample variance.
Essentially, this converts paleontological time-series data into standard deviation units, similar to the computation of evolutionary rates in haldanes. This operation does not change the relative fit of models, but it does facilitate the comparison of parameter estimates across time-series with different units.
the converted paleoTS
object.
Gene Hunt
Hunt, G. 2006. Fitting and comparing models of phyletic evolution: random walks and beyond. Paleobiology32:578–601.
y<- sim.GRW(20, 0, 1, vp=10) ys<- std.paleoTS(y) fit3models(y) fit3models(ys) # note Akaike weights do not change from standardization