Forest Biometrics - FOR 205
Lab 4 – Fall 2015
Each person will turn in one worksheet and one set of answers to the problems in Part II. No
cover page is necessary. Place all crew members’ names at the top of this page. This lab will be
due one week from the day it was assigned
Part I
We will measure ten logs at a local saw mill. Using a caliper or D-tape and logger’s tape, fill in
the attached worksheet. Small end diameters are inside-bark measurements to the nearest 0.1
inch and scaling diameters are recorded to the nearest inch. Log lengths should be rounded
down to the nearest 2-foot class to a maximum length of 20 feet. Do not measure any logs with a
small-end diameter > 30 inches.
Part II
Place only the answer to each question in the appropriate space below and show all work on
separate pages, if necessary. Make sure the work is labeled clearly as to which question it
pertains, so that partial credit may be given.
1. Estimate the Doyle, International ¼”, Scribner, and Scribner Decimal C board-foot content
for each log that you measured in part 1. You can put your answers on the worksheet.
2. Compare the board-foot volumes that you calculated in question 1. If the volumes are
different, why do you think these differences occur?
1
3. Which board-foot estimate is closest to the true board-foot content? Why is this the case?
4. In general for all logs, how do the board-foot estimates from the log rules compare to each
other? Why?
5. Calculate the mean, variance, standard deviation, standard error of the mean, coefficient of
variation, bound on error, and 95% confidence interval (t = 2) for the four board-foot volumes
from the Doyle, International ¼”, Scribner, and Scribner Decimal C log rules. Remember to
show your work and include the units for all statistics.
Remember that these questions will be similar to those that will be asked on the test. Be sure
that you can work any of them forwards and backwards. If needed, change some of the numbers
and work the problems again. Do not hesitate to come by my office and ask questions.
2
Lab 4 Worksheet
Log
Number
Small End
Diameter
(inches)
Scaling
Diameter
(inches)
Log Length
(feet)
Doyle Scale
(bf)
1
2
3
4
5
6
7
8
9
10
3
International
¼” Scale (bf)
Scribner Dec
C Scale (bf)
Scribner Scale
(bf)