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We can save a client a tremendous amount of cruise expense by using
a procedure we've developed to make a simple estimate of the gross
volume of a timber stand. We completed ocular estimates for approximately
700 individual stands in a one-month period for a large client and
were within 3% of the actual tract volume. This large project allowed
us to check enough of our ocular estimates to offer clients a statistically
supported adjusted estimate method.
We've used the formula: Number of Equivalent Cruise Plots
= (a default CV / SE) ^2 to calculate how many cruise plots
our past ocular estimates are equivalent to. Our ocular estimates
are the equivalent of doing 5 standard cruise plots, with a standard
error of 30%. This method should never be used when the time and
funds are available for enough cruise plots to be completed in the
stand to achieve an industry-accepted sampling error of 10% or less.
The approximate cost to complete 5 standard cruise plots in a timber
stand would be $83 and take almost 2 hours. The approximate cost
for our 15-minute ocular estimate on the same stand would be just
$17; 20% the cost to achieve the same accuracy level. No travel
expenses are included in this comparison.
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