02 Scientific Method
Environment & Ecology
The nature of science• Science:
– A systematic process for learning about the world and testing our understanding of it
– The accumulated body of knowledge that results from a dynamic process of observation, testing, and discovery
• Science is essential:– To sort fact from fiction – Develop solutions to the problems we face
Vaccines cause autism
Fact or Fiction?
Discovery or observational science.
Hypothesis-driven or experimental science.
Two Primary Approaches to ScienceScientists test ideas
Hypothesis-Driven Studies
Discovery/Observational Studies
Applications of science
Restoration of forest ecosystems altered by human suppression of fire
Policy decisions and management practices
Energy-efficient methanol-powered fuel cell car from DaimlerChrysler
Technology
The scientific method
• Observations • Question • Formulate Hypothesis • Conduct Experiment • Analyze Results • Conclusions • Discussion
A technique for testing ideas
Testing predictions• Experiment: an activity that tests the validity of a
hypothesis• Variables: conditions that can be manipulated
and/or measured– Independent variable: a condition that is manipulated– Dependent variable: a variable that is affected by the
manipulation of the independent variable• Controlled experiment: one in which all variables
are controlled– Control: the unmanipulated point of comparison– Treatment: the manipulated point of comparison
• Data: information that is generally quantitative (numerical)
Experiments test the validity of a hypothesis
• Manipulative experiments yield the strongest evidence– Provides the strongest type of evidence– Reveal causal relationships: changes in independent
variables cause changes in dependent variables– But many things can’t be manipulated: long-term or
large-scale questions (i.e., global climate change) • Natural experiments show real-world complexity
– Only feasible approach for ecosystem or planet-scale– Results are not so neat and clean, so answers aren’t
simply black and white
Scientific Method: ExampleExample
Many habitats are fragmented.
Corridors are being constructed between patches.
Do they really work?
Observations
Scientific Method: ExampleExample
Corridors facilitate movement of butterflies between isolated habitat patches
Common buckeye Variegated fritillary
Hypothesis
Butterflies will move into connected habitat patches more frequently than into unconnected habitat patches
Prediction
Experiment and/or data collection
Experiment results
Observation:
Question:
Hypothesis:
Test hypothesis:
Analyze Results:
Draw Conclusion:
Ben Franklin & the Gulf Stream
1996
1786
Pisaster
Paine’s study on Pisaster and blue musselsWhat effect does starfish removal have on community structure?
chiton limpet
mussels (Mytilus)
barnacles
Keystone Species
Paine’s study on Pisaster and blue mussels
Coral Reef Benthic Habitat Point and Area
AssessmentsKaneohe Bay, HI
• Large sample size• Random sampling
Mangrove Study
Do sponges affect mangrove root growth?
Select a large sample size
Randomly divide the sample into 2 groups
Treat the groups equally in all ways but oneObserve or make measurements
Compare results
Mangrove Study
Inquiry1. What is the difference between a
hypothesis, theory and law?2. Can a theory ever be proven?3. In the mangrove study, what is the
dependant variable?4. State Ben Franklin’s hypothesis.5. In Paine’s study on Pisaster, what
role did blue mussels play?
QUESTION: Review
Which is the correct order of the scientific method?
a) Observation, question, hypothesis, testing, results
b) Hypothesis, observation, testing, question, results
c) Observation, question, testing, results, hypothesis
d) Question, observation, hypothesis, testing, results
QUESTION: Interpreting Graphs and Data
What happens if test results reject a hypothesis?
a)The scientist formulates a new hypothesis.
b) It shows the test failed.c) The scientist should be fired.d)The scientist used faulty data .