Estimating relative population size or rate of change

[Kiran Hazra]

My goal using the Bayesian skyline is to identify when changes in population size occurred, with the smallest confidence intervals possible. Is there a way to estimate historic population sizes relative to present-day population size, rather than estimating the absolute value? This may help decrease the confidence interval size.

 Alternatively, is there a way to plot the estimated rate of change, instead of estimated population size?

Thank you