Data analysis was conducted in R \cite{Team2015} and RJAGS \cite{Plummer2015}, utilizing a Bayesian approach to estimate the heritability of growth-strain at the family level. The effect of coppicing is included as a fixed effect. Specimen groups were grown during different time periods and for different rotation lengths, group is included as a random effect. The “Splitting” test is physically constrained to positive values, as the opening cannot be reduced in the presence of compression at the stem surface and tension at the pith resulting in left censored data. Bayesian frameworks provide the ability to simulate partially observable data, and therefore reducing the systematic errors which occur due to left censoring. Here the left-censored initial values are sampled from a uniform distribution between -1.5 and 0.