Janka Hardness data

Arguments

Dens the air-dry timber density for the tree, in pound per cubic foot
Hard the corresponding Janka hardness, in Janka units.

Format

The data frame janka has two components:

Description

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.

Details

A low-degree polynomial regression may be an appropriate model. A log or square-root transformation of hardness may also be useful.

Source

E. J. Williams (1959) Regression Analysis. Wiley, New York. p. 43.


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