Environmental Science / Unit 1: Introduction to Environmental Science
1.3 The Scientific Method in Environmental Studies
Notes
Environmental scientists use the scientific method, but often cannot run perfect experiments on whole ecosystems, so they also use observation and models.
- Steps: observe, ask a question, form a testable hypothesis, collect data, analyze, draw a conclusion, and share results.
- In an experiment, the independent variable is changed by the scientist; the dependent variable is measured; controlled variables are kept the same.
- A control group gets no treatment so results can be compared.
- Peer review means other experts check the work before publication.
- Correlation does not prove causation: two things that change together may both be caused by a third factor.
- Example: to test if fertilizer affects algae, add different amounts to identical tanks (independent variable: fertilizer; dependent: algae mass).
Practice
In an experiment testing how fertilizer amount affects algae growth, the dependent variable is:
The dependent variable is what is measured as the result.
Why is a control group included in an experiment?
Without a control, you cannot tell whether the treatment caused the change.
Ice cream sales and shark attacks both rise in summer. A student concludes that ice cream causes shark attacks. The error is:
A third factor (summer weather and more swimmers) explains both trends.
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