Experimental Design Scientific Method Intro Chapter P 6-7 Scientific Method Intro Chapter P 6-7.
Scientific Method and Experimental Design
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Transcript of Scientific Method and Experimental Design
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Scientific Method
Hypothesis
Controlled Experiment and Variable
Independent and Dependent Variable
Sample Size and Validity
Scientific Method and Experimental Design
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Steps of the Scientific Method
1. Make observations.
2. Ask a question.
3. Form a hypothesis.
4. Test the hypothesis.
5. Analyze the results.
6. Draw conclusions.
7. Communicate the results.
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Hypothesis
An explanation of a natural event or observation that can be tested by additional observations or experimentation
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Example of Hypothesis
Observation: The population of tiger salamanders declined 65% between 1984 and 1988
Hypothesis: Acids that were formed in the upper atmosphere by pollutants were falling onto mountains in the winter snows
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Controlled Experiment and Variable
Tests one variable at a time (experimental variable)
Controlled experiments include 2 groups:
Experimental Group
Exposed to experimental variable
Control Group
Not exposed to experimental variable
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Independent and Dependent Variables
Independent variable: The factor that is deliberately manipulated in an experiment (also called experimental variable)
Dependent variable: The variable that is changed or determined by manipulation of the independent variable. It is what is measure in the experiment
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Sample Size
Sample Size (N)
•The number of subjects involved in experimentation
•Increasing N
• Decreases impact of chance events and error
• Increase reliability of results
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Validity
The extent to which experimental results can be generalized to other settings or situations
To increase validity, increase N