Douglas Fir Biometrics

Description: Students measure the heights and circumferences of a sample of Douglas fir trees using simple devices and right-triangle trigonometry. Students then take an exploratory data analysis approach to determine which of several functions best fits the (circumference, height) data. Students extrapolate beyond the data to predict the height of a 700-year-old Douglas fir from its circumference.

The exercise focuses on measurement and errors, modeling with functions, correlation, extrapolation and outliers. Inexpensive inclinometers for measuring the angle from the horizontal are easily obtained.