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FOR 250 - Stats & Measurement > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

What is a chain?

A
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2
Q

How many chains = 1 mile?

A

80

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3
Q

How many feet are in 1 mile?

A

5280

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4
Q

How many square feet are in an acre

A

43560

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5
Q

How many square chains is an acre

A

10

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6
Q

What is magnetic declination?

A

It is the azimuth (°) difference between True North and Magnetic North that must be accounted for when navigating with a compass.

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7
Q

What are the steps for dead reckoning with a compass?

A
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8
Q

What are the steps to take an azimuth with a compass if you are given an angle?

A
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9
Q

How do you find the circumference, radius, and area of a circle?

How do you calculate basal area of a tree, and what unit is it expressed in?

A
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10
Q

How do you find the basal area of a tree in ft2 if you know the DBH in inches?

How do you calculate the basal area per acre?

A

DBH2 x .005454

Calculate the BA of each tree in a plot, then sum those. Multiply that number by the BA factor, which is the denominator of the fraction used to define your plot size (a 1/10 acre plot has a BA factor of 10). This is expressed in ft2/acre.

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11
Q

How do you measure DBH using a d-tape/loggers tape?

How do you measure DBH using a Biltmore stick?

A

Measure around the tree 4.5 ft off the ground from the uphill side of the tree, making sure the tape is perpendicular to the direction of tree growth. Expressed in inches to the nearest 1 decimal place.

Hold the stick 25” away from your eyes and visually align the 0 end of the stick with the left side of the tree trunk. Without moving your head (only move your eyes) check where the other side of the tree trunk falls on the measurement scale of the stick. Move 90 degrees around the tree, take the measurement again, and average these 2 measurements.

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12
Q

What is a hypsometer?

What is a Merritt hypsometer?

What is a clinometer? What are standard distances for a clinometer?

A

Hypsometer - An instrument for measuring tree heights

Merritt hypsometer - scale on a Biltmore stick intended to measure tree height in 16’ logs from a distance of 1 chain (66’) when held 25” from the eye (unless custom for your arm length)

Clinometer - an instrument used to measure slope angles, which can then be used with trigonometric functions to estimate tree height

A Suunto clinometer uses a standard horizontal distance of 100’, a topographical or forester’s clinometer uses a standard distance of 1 chain (66’)

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13
Q

How do you find side a given angle A and side b?

A
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14
Q

What is cull?

A

something rejected especially as being inferior or worthless

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15
Q

What are gross volume and net volume? What’s the process for getting to net volume?

A
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16
Q

How would you calculated the deductions for each of these defects?

A
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17
Q

What are some examples of defects that would decrease the value of a log?

A
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18
Q

How do you determine the section of the tree (log) that you will grade, and which face of that log to grade?

A
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19
Q

What are log scaling and grading?

A
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20
Q

What are log rules for and what are the 3 most used ones?

A
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21
Q

What is the Doyle log rule and what are its pros/cons?

A
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22
Q

What is the Scribner log rule and what are its pros/cons?

A
23
Q

What is the International 1/4” log rule and what are its pros/cons?

A
24
Q

What is a log?

What is a bolt?

What is scaling?

A
25
Q

What is a Rick? What is a standard Cord?

A
26
Q

What is a face cord?

A
27
Q

What is a board foot of wood?

A
28
Q

1 MBF =

? board feet

? cubic feet

? cords

A
29
Q

1 cubic foot =

? cubic inches?

? board feet?

A
30
Q

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

A

Nominal

Ordinal

Interval

Ratio - most common in forestry

31
Q

What is nominal measurement?

A

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.

32
Q

What is ordinal measurement?

A

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

33
Q

What is interval measurement?

A

•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.

34
Q

What is ratio measurement?

A

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.).

35
Q

Define accuracy and precision

A

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

Precision = the clustering of sample values about their own average

36
Q

What is bias, as it relates to data?

A
  • 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.
37
Q

Relate each target to bias, precision, and accuracy

A
38
Q

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

A

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

39
Q

Define statistics

A

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

40
Q

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

A

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.
41
Q

Differentiate between continuous and discreet variables.

A
42
Q

What is normal distribution and the central limit theorem?

A
43
Q

What are mean, median, and mode?

A
44
Q

What does this notation mean?

A
45
Q

What does the ‘i’ subscript indicate in this notation?

A
46
Q

What does this notation mean?

A
47
Q

What is range?

A
48
Q

For normally distributed poplulations, what percentage of the observations will be within 1 or 2 standard deviations of the mean?

A
49
Q

How do you calculate variance and standard deviation?

A
50
Q

How do you calculate the coefficient of variation (cv)?

A
51
Q

What is a population vs a sample?

A

A population is the entire group of units that you want to draw a conclusion about. It could be a finite or infinite population. A sample is the specific group of units that you will collect data from. The size of the sample is always less than the size of the population.

52
Q

What’s this formula for and how do you use it?

A

Ex2 = square each x, then sum those results (sum of squares)

(Ex)2 = sum all x’s, then square the total (sum, squared)

n = number of observations

53
Q

What’s this formula for and how do you use it?

A

find the variance, then the standard deviation is the square root of that answer

54
Q

What’s this formula and what is it used for?

A

FOR 250 - Stats & Measurement (4 decks)

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