Week 5 Worksheet_ Regression and Correlation
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Feb 20, 2024
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MATH 201 Statistics for Environmental Professionals ● Worksheet 5
Name: Orissa Pollard
Suppose that you work for the conservation of natural areas at the Bureau of Land Management. Your
section concerns the effect of wildfires on natural areas. Your supervisor asked you to analyze the
temporal trend in wildfires. In particular, she is interested in the following associations:
1.
Has the number of wildfires per year increased?
2.
Has the total burned area (in acres) per year increased?
3.
Has the burned area (in acre) per fire increased?
The accompanied data file contains the number of wildfires, total burned area, and burned area per fire in
the U.S. from 2000 to 2019.
Question 1
. Using Excel, create three scatter plots which show each association (year and number of
wildfires, year and total burned area, and year and burned area per fire). Clearly label the graphs. Note
that year should be on the x-axis. Attach the scatterplot to this report. Refer to textbook 12.2. (15 pts.)
Figure 1: Scatterplot showing the relationship between Years vs. Number of Fires
Figure 2: Scatterplot showing the relationship between Year vs. Acres Burned
Figure 3: Scatterplot showing the relationship between Year vs. Acres Burned per Fire
Question 2.
Using the scatter plots created in Question 1, perform a visual assessment. Describe the
trend, strength, and shape of each association. Refer to textbook 12.2. (15 pts.)
Association between year and number of wildfires:
Trend:
Decreasing
Strength:
Moderate to Strong
Shape:
Linear relationship
Association between year and total burned area:
Trend:
Increasing
Strength:
Moderate
Shape:
Linear relationship
Association between year and burned area per fire:
Trend:
Increasing
Strength:
Moderate to Strong
Shape:
Linear relationship
Question 3.
Using the provided Excel sheet, calculate the correlation coefficient (r) and coefficient of
determination (r
2
) for each association and determine the values in the below table. Refer to textbook
12.3. (15 pts.)
Variables
Correlation coefficient
(r)
Coefficient of determination
(r
2
)
Year and number of wildfires
-0.4929
0.2429
Year and total burned area
0.1181
0.0139
Year and burned area per fire
0.3714
0.1379
Question 4.
Based on the visual assessments and correlation coefficient in questions 2 and 3, select the
strongest linear relationship of the three associations. Clearly, mark one. (5 pts.)
A.
Association between year and number of wildfires
B.
Association between year and burned area
C.
Association between year and burned area per fire(r= .37)
Question 5.
Using the provided Excel sheet, determine the regression equation for the association you
have selected in question 4. Note that the year is the independent variable. Write down the equation. Refer
to textbook 12.3. (15 pts.)
Burnedareaperfire = - 10465.94+5.28Year
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