5/24/2010
The Scientific Method
7 Steps to a Logical Process
1. Hypothesis versus Theory
Hypothesis:
• Educated guess
• Outcome
• If I do….then I
expect……
• correct or
incorrect
Theory:
• Established
idea
• Factual
• Experiments
• Data
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Control versus Experimental groups
Control:
• comparisons
• “Normal”
condition
• Eliminates
bias
Experimental
• one variable
• one condition
different from
control
• more variables =
• more controls
Experimental Variables:
• Independent Variable:
One condition that is
changed from the
control group
• Example:
control = normal plant
growth conditions
independent variable=
growth under no
fertilizer
• Dependent Variable:
the condition
measured as a result
of adding the
independent variable
• Example:
• Measure growth in
height as a result of
no fertilizer
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3 & 7.Data versus Opinion…...
Data:
• Factual
• Measurable
• Replicates
Opinion:
• Personal
• Inferences
versus
observations?
• bias
4. Types of Experimental Bias
as opinion:
• Expectations
• Influences
results
• Psychology
experiments
in design:
• Unequal
treatment
• Poor Controls
• Plant
experiments
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Replicates of each group:
• Replicate=
• “Make an exact copy”
• Each group must have
more than one setup
• for comparing results
& verifying test
conditions
• Minimum of 10
replicates
Scientific Data Must Be…..
• Measurable
• Quantifiable
• NOT opinion
or judgment
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7 Steps of the Scientific
Method
• ? Different
• ? Precise
• ? Steps
necessary?
• ? Most
important
1. Identify the question
• What
• How
• Not “Why”
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2. Background research…...
• Libraries
• Internet
• Experiments
• Researchers
• Interviews
3. State you hypothesis
• Educated guess
• Outcome
• Cause……leads to
effect
• IF I do………then I
expect………….
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4. Design an experiment
1.Control
2.Experimental
Group
3.One variable
4.Replicates
5. Collect data
• Measurable
• Machine
• Tool
• Color chart
• Factual
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6. Analyze data
• Agreement in
replicates
• Good
Controls
• Graph trends
7. Communicate results
• Publish
• Conference
• Web page
• Design errors
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CONCLUSION:
• Which Step?
• What is
needed?
• Measurable
Data
Characteristics of Living Things:
• Structure & organization: cells, DNA, tissues
& organs
• Reproduction
• Growth & development
• Respond to their environment
• Metabolism: sum of all chemical reactions
• Maintain homeostasis by using energy
• Adapt and evolve
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