1. CHE116 Week 1 Scientific Method
Guidelines for performing scientific studies
Proceed in a logical order (systematic experimentation)
Eliminate personal bias
(Actual number of steps will vary, depending on reference consulted)
CHE116 Week 1 Scientific Method
CHE117 Fall 2011 LStewart

2. CHE116 Week 1 Scientific Method
Multiple Steps
Observation of phenomenon/Question asked
Background information/Literature search
Develop hypothesis (tentative explanation)
Test hypothesis with experiments
Conclusion
Also:
Communicate results
Develop Theory (explanation that has been tested many times [by many scientists] and still works)
CHE116 Week 1 Scientific Method

3. CHE116 Week 1 Scientific Method
General “Rules”
Be unbiased when acquiring data
Be unbiased when interpreting data
Use all data unless something truly went wrong with the experiment
Hypothesis should fit the data, not the other way around (never force data to fit the hypothesis)
Change the hypothesis as needed (don’t change the data)
CHE116 Week 1 Scientific Method

4. Example: Plant Growth with Fertilizer
Plant With Fertilizer
Plant Without Fertilizer (control)
(Same conditions to eliminate temperature, water, sunlight variations)
CHE116 Week 1 Scientific Method

5. CHE116 Week 1 Scientific Method
Example
Observation: Plants that are given fertilizer seem to grow larger than “usual”
Hypothesis: Fertilizer causes plants to grow larger, faster, better
Experiment to test hypothesis:
Give a plant a known amount of fertilizer and measure growth
Compare plant growth to same type of plant that was not given fertilizer, other variables identical
CHE116 Week 1 Scientific Method

6. CHE116 Week 1 Scientific Method
Other Considerations
Prevent bias - look at data A and data B, not “plant with” and “plant without” (be blind)
Make conclusion about hypothesis: Is it supported by data or does hypothesis need to be re-evaluated and then retested? Does experiment need to be redesigned?
Continue to verify hypothesis with other experiments (other plants, other scientists)
CHE116 Week 1 Scientific Method