Scientific Method
Somewhere, something
incredible is waiting to be
known.
~Carl Sagan
Scientific Method
Research is going up alleys
to see if they are blind.
~Marston Bates
Observation
Information about our world that
we obtain directly from our senses.
Quantitative Observation:
Based on exact measurement
•Example: The room is 8 meters wide.
Qualitative Observation: Not easily measureable
•Example: This table is smooth.
Inference
Logical interpretation or explanation based
on observations and prior knowledge.
Example: That car is fast because it is a red Mustang.
Inference vs. observation
A few observations and
much reasoning lead to
error; many observations
and a little reasoning lead
to truth.
~Alexis Carrel
Inference vs. observation
DON’T JUMP TO
CONCLUSIONS!
I thought
there was
going to be
a net…
Base your conclusions
on careful observations.
List FIVE observations regarding the cartoon above.
List FIVE inferences regarding the cartoon above.
Hypothesis
• Educated guess
based on
observations
• Suggests a possible
explanation or
answer to the
“question”
• Suggests cause and
effect relationships
• Testable
• Predicts possible
outcomes of a study
Hypothesis
• Educated guess
based on
observations
• Suggests a possible
explanation or
answer to the
“question”
• Suggests cause and
effect relationships
• Testable
• Predicts possible
outcomes of a study
Experiment
•Procedure designed to test validity of hypothesis
•Involves collection of data
Variables
Constants
Factors that do not remain
the same in an experiment.
Dependent variable:
Factors that remain
unchanged in an experiment.
•
Factor that changes in response to
changes in the Independent Variable.
Independent variable:
•
Factor that the researcher chooses to
manipulate in order to assess its
effects another variable.
Experimental Group
A group of subjects or conditions that will
be exposed to changes in order to obtain
measureable data.
Control Group
A group of subjects or conditions that is
matched as closely as possible with the
experimental group, but is not exposed
to any experimental treatment.
Used as a basis for comparison to
aid in determining significance of data
obtained in the experiment.
Keys to a Good
Experiment
One independent variable!
Control group
Measureable results
Collect lots of data
Analysis
Interpret data collected.
Perform any calculations.
Prepare any graphs or charts.
Conclusion
Make statement that accepts or rejects
hypothesis based on analysis of data.
Make recommendations for further study or
possible improvements to the procedure.
Analysis & Conclusions
Testing leads to failure,
and failure leads to
understanding.
~Burt Rutan
Observe and Question
Form Hypothesis
Conduct Experiment
Collect Data
Analyze Data and
Form Conclusion(s)
Continental
Drift Theory:
WHAT IS A THEORY?
Big Bang Theory
WHAT IS A THEORY?
A scientific theory begins as a HYPOTHESIS, which
is an educated guess.
With experimentation, a hypothesis can be either
disproven or supported, but cannot be proven.
As more and more support is gathered for the
hypothesis, without being disproven, it may
become widely accepted as a good explanation of
a phenomenon.
At this point, it may be considered to be a
THEORY.
WHAT IS A THEORY?
We don’t regard any
scientific theory as the
absolute truth.
~Kenneth Miller
WHAT IS A THEORY?
Science is organized
common sense where many a
beautiful theory was killed
by an ugly fact.
~Thomas Huxley
WHAT IS A THEORY?
Science never gives up
searching for truth, since it
never claims to have
achieved it.
~John Charles Polanyi
1
2
3
4
5
6
7
• How reliable is the source of the claim?
• Was the information obtained using good science?
• Were the data from the experiments interpreted correctly?
• Are there other possible explanations for the results?
• Is the information consistent with other sources?
• Are there other possible explanations for the results?
• Is the information consistent with other sources?
Remember! Think critically!
Example: Vaccines cause autism?
Cleveland Plain Dealer
January 25, 2011