This study examines the relation between breast height diameter of ponderosa pine tree and volume of timber. Breast height diameter is measured 4.5ft above the ground. Volume is measured in board feet. A board foot is a one twelfth of a cubic feet.
An exponential and a power model will be formed and evaluated to nd the most graphically tting model for given data
Firstly, exponential model will be formed.
The parameters a and b must be estimated for forming the model. For that purpose, transformed data can be examined as follows
This model seem to be highly tting with the data until 45 inches of breast height diameter(DBH). Quality of a study depends on the data
available for the study. Since a good range of data were available for this study, the matched model has a sucient ability to predict the timber
volume of a ponderosa pine tree using its DBH. Hence this model is economically valuable in such industry.