Environmental History, Politics, and Economics
Part I: Hypothesis Formulation
1. Research the meaning of null hypothesis. Describe how and why it is used in experimental design.
Cite your references as per APA.
2. The following are observations of environmental phenomena. Rewrite each observation into a formal,
testable null hypothesis and a formal, testable alternate hypothesis. Identify dependent and
independent variables for each hypothesis statement. Put the dependent variable in bold font and
underline the independent variable for each. Remember that independent variable means what you
can control and manipulate in the experiment and dependent variable, as the name implies, is
dependent on the independent variable and is what you measure in the experiment.
a. Eggshells produced by birds that were exposed to mercury seem to be thinner.
b. Plants near roads where salt is used in the winter appear smaller.
c. Gulls covered with oil do not look like they can fly.
d. There seem to be fewer squirrels in the snow.
e. Trees in areas where there is acid precipitation look shorter.
Part II: Presenting Your Results
1. Create a table using the following data. Be sure to include a title and labels for the columns. The data
is the top ten national sources of impairments (degradation of the designated water quality standards)
and the associated number of impaired miles for rivers and streams in the United States (US EPA,
urban-related storm water runoff—38,114.89; unknown—91,823.72; silviculture—8,463.23; natural—
41,764.05; permitted municipal sewage—32,438.24; resource extraction (mining)—28,722.37;
industrial discharges—17,405.02; hydromodification (alteration of the flow of water)—79,399.66;
habitat alternation (but not hydromodification)—51,297.85; and agriculture—113,662.70.
2. Your hypothesis was that industry is the leading cause of stream impairment in the United States.
Based on the data presented in question 1, can you support this hypothesis?
3. Using the data from question 1, create a histogram. In one paragraph, discuss the visual impact of
the table compared to the histogram. Be sure to include a title and labels for the columns. You can
use Microsoft Excel to create the histogram.
4. Create a line graph using the following data, which are the mean, annual ambient concentrations of
measured at Mauna Loa, Hawaii (NOAA, 2008b). Be sure to include a title and label. Briefly
SC4730: Week 2 Environmental History, Politics, and Economics
The Scientific Method
describe what the data suggests is happening to CO
levels? You can use Microsoft Excel to create