janka {Rnotes} | R Documentation |
Janka hardness is an important structural property of Australian timbers, but is difficult to measure directly. It is, however, directly related to the density of the timber which is relatively easy to measure. In an effort to develop a method of predicting Janka hardness from density, the Janka hardness (here considered the response) and the density of 36 Australian eucalypt hardwoods was measured.
The data frame janka
has two components: dens
is the timber
density for the tree and hard
is the corresponding Janka hardness.
A low-degree polynomial regression may be an appropriate model. A log or square-root transformation of hardness may also be useful.
Polynomial regression. Transformations.
E. J. Williams, Regression Analysis, Wiley, 1959