Intro Material

Question 1

What is mensuration?

Answer 1

the art and science of locating, measuring and calculating the length of lines, area of planes and volumes of solids.

Question 2

What is forest mensuration?

Answer 2

Measuring the forest (logs, trees, stands)

The art and science of providing the quantitative information about trees and forest stands necessary for forest management, planning and research.

Another term for this is timber cruising.

Question 3

What are each of these abbreviations?

BA

BAF

Cd

DBH

Dib

Dob

MBF

Answer 3

• BA – basal area
• BAF – basal area factor
• Cd – cord
• DBH – Diameter at breast height
• Dib – Diameter inside bark
• Dob - ?
• MBF – thousand board feet

Question 4

What are the 4 scales of measurement? Which one is most commonly used in forestry?

Answer 4

Nominal

Ordinal

Interval

Ratio - most common in forestry

Question 5

What is nominal measurement?

Answer 5

Categorical data and numbers assigned for identification only, for example we might name the first species we encounter in the woods as species 1 and so forth. No meaningful analysis (except frequency of occurrence) can be performed on the data. Examples: political party, religion, etc.

Question 6

What is ordinal measurement?

Answer 6

used to express order within a series. An examples would be lumber grades where 1 is greater value or quality than 2 and 3 but the difference from 1 to 2 may not be the same as the difference between 2 and 3

Question 7

What is interval measurement?

Answer 7

•a scale of uniform gradations representing quantity but zero is just another point of measurement. Temperature is a good example. The distance from 30 to 40 degrees is the same as the distance from 70 to 80 degrees.

Question 8

What is ratio measurement?

Answer 8

most commonly used in forestry. Ratio scales are interval scales but a value of 0 indicates zero of the thing measured. There are no negative numbers in ratio scales. Ratio implies that a value of 2 indicates twice as much of a measured item than a value of 1 (distance, weight, etc.).

Question 9

How many square feet are in 1 acre?

Answer 9

43560 sq ft

Question 10

Define accuracy and precision

Answer 10

Accuracy = the success of estimating the true value of a quantity

Precision = the clustering of sample values about their own average

Question 11

What is bias, as it relates to data?

Answer 11

• A systematic distortion in the data which may be caused by poor measurements, bad sample selection or incorrect estimation procedures.
• This could be caused by defective or improperly calibrated equipment or measuring procedures. Also by user error - failing to correct for declination, slope, etc.

Question 12

Relate each target to bias, precision, and accuracy

Answer 12

Question 13

Relate each target to bias, precision, and accuracy. What do the blue lines on the top right target represent?

Answer 13

Bias can be measured, as indicated by the gap between the blue lines.

Question 14

Define statistics

Answer 14

the art and science of gathering, describing, analyzing, summarizing and interpreting data to give us new information and knowledge

Question 15

In forestry, why do we generally sample instead of taking a complete census?

Answer 15

Reduced Cost • For populations having an extremely large number of individuals (like forest trees), measuring each individual would be impractical. Neither the time nor the money is available to do such an inventory. Additionally, the inventory costs of doing such an inventory could exceed the value of the sale.

• Greater Speed • Sampling reduces the magnitude of the job, allowing the task to be completed in a shorter period of time. Not many timber sales would make it to market if the volume is measured on all of the trees and it takes ten months to do the sale prep work.
• Greater Scope • Sampling provides the ability to study a larger area and include diverse information about the population. Additional information such as species present in the population, type of defect, or other conditions in the population can be included when sampling is used.
• Greater Accuracy • Often overlooked is the quality of work suffers when budgets and resources are stretched too thin. Good measurements on a sample of individuals provide more reliable information than bad measurements on the entire population.

Question 16

Define probability in terms of a ratio and give an example

Answer 16

A balanced coin flipped in an unbiased way results in heads or tails (each with an equal 50% chance)

• Chance of heads = one/two possible outcomes

Question 17

What is this notation?

4!

Answer 17

It indiccates a factorial of 4

4! = (4)(3)(2)(1) = 24