DEFINITION OF SCIENTIFIC METHOD
SCIENTIFIC METHOD APPLIED
REPLICATION AND PEER REVIEW
DEFINITION OF SCIENTIFIC METHOD
The scientific method:
• Applies to a measurable problem
• is a step-by-step procedure to solve a stated
problem through experiments or observation
• Outlines a set of requirements at every step
• Does not allow shortcuts in the main steps.
Forms of scientific method
• The scientific method can be based on inductive
reasoning or deductive reasoning. 
• Inductive reasoning. Reasoning from the
particular to the general.
– Based on experiments. Better suited for physical
sciences. Causal action [Most used]
– Based on observation/interviews. Better suited for
Anthropology, Astronomy, etc.. Descriptive
• Deductive reasoning. Reasoning from the general
to the particular.
Phase 1 – PROBLEM STATEMENT
The problem should be:
• Measurable (submits to the scientific method)
• Clearly and concisely stated
• If necessary, divided into simpler measurable
Problem Statement - Examples
General Negative impact of drug-related wars on populations
Specific Drug-related deaths in Juarez, Mexico, in 2009 
General ADD in teens
Specific (Fictional) ADD in teens who do not participate in athletic activities
for more than one hour/week
General Big bang scientific controversies
Specific Failure of the big bang theory to account for the
homogeneity of the cosmic microwave background (CMB)
Problem Statement – Questions
Steps to refine a problem:
• Benefits (immediate, long-term, etc.)
• Timeline (when did the problem happen?)
• Localization (narrow the scope of problem)
• Population (focus on specific groups)
• Urgency (deadline to solve a problem)
Once the problem has been adequately stated,
• Do background research on the problem:
– potential solutions may already exist
– Helpful discussions or hypotheses may exist
• If the problem has been solved, move on!
• Else, revise the problem or select a new one.
Problem Statement - Summary
Phase 2 - SCIENTIFIC METHOD
The scientific method is a tool to solve the
• It is composed of four steps in order:
– Formulation of a hypothesis.
– Conducting experiments or making observations.
– Testing resulting data.
– Reaching a conclusion.
Formulating a Hypothesis –
A hypothesis is an educated guess about solving
the stated problem.
• Specific to the problem
• Clearly stated (preferably as a statement)
• Verifiable (directly or indirectly)
Formulating a Hypothesis – Examples
Drug-related deaths in Juarez, Mexico, in Stop weapons and money illegally
2009 imported from U.S.
ADD in teens who do not participate in Use drugs D1 and D2, alone or in
athletic activities for more than one combination to eliminate deficit
(Fictional problem) (Fictional drugs)
Failure of the big bang theory to account Inflation, hundredths of a second prior to
for the homogeneity of the cosmic big bang, spread elements all over at
microwave background (CMB) radiation speeds higher than speed of light
Testing Your Hypothesis –
• Hypothesis is tested through experiments and
• Experiments and observation must be related to the
• Relationships: cause-and-effect or correlations
• Tools must be readily available
• All experiments, observations and results recorded
• No bias. Do not favor supporting data
• Do not use outside elements (politics,…) to force
acceptance of hypothesis.
Hypothesis Testing –
Experiments Observation Indirect observation
• Determination of target • Reliable • Indirectly tested
• Baseline assessment
• Randomization – random • Repeated • Mathematical calculations
assignment of subjects to validated
• Planned [design of experiment] • Passive observer
- Proof by [validity/reliability]
• Replicable contradiction (null • Reproducible
• Replicable [validity/reliability] • Reproducible
Hypothesis Testing –
ADD Drugs Hypothesis Juarez Hypothesis Inflation hypothesis
[Experimental] [Descriptive] [Indirect observation]
• Set baseline based on • Trace weapon origin • Measure non-uniformities using
information from probes
subjects - COBE (1992)
- WMAP (2003)
• Create 1 control and 3 • Trace money to its
experimental groups source
• Apply tests to groups • Collect/study
bullets from victims
• Document process • Document process • Document process
• Replicate tests
• Measurements resulting from experiments
and observations should be collected,
analyzed and documented
• Resulting data should be used to validate or
• If a hypothesis is refuted (null hypothesis
succeeds), a new hypothesis should be
constructed and the process restarted.
Data Analysis – Examples
ADD Drugs Juarez Hypothesis Inflation hypothesis
• Test results • Against Hypothesis • Hypothesis on predicted non-
inconclusive [Null - Most weapons come uniformities validated by:
hypothesis was not from Central and South - Probe Cosmic Background
rejected – type I America (NRA) Explorer (COBE) in 1992
error?] - Weapons to Cartel are - Probe Wilkinson
provided by corrupt police Microwave Anistropy Probe
and military (WMAP) in 2003
Null hypothesis not • In favor of Hypothesis accepted!
rejected! - Investigations from
Mexico are validated
- U.S. government
• Unsolicited replication of experiments
• Peer review
Scientific Method- Summary
Provide Hypothesis No
Check Hypothesis No
Conclusive? Test again
 Jere H. Lipps. http://palaeo-electronica.org/2000_2/editor/jere.htm
Department of Integrative Biology and Museum of Paleontology, University of
California, Berkeley, CA 94720, USA. Nov. 2000
*2+ CBS’ Face the Nation. http://www.msnbc.msn.com/id/30179854/
Mexico: Weapons from U.S. fuel drug war. Associated Press, April 12, 2009
 Brad Lemley. Guth's Grand Guess.
d%20Guess. April 1, 2002
 ALAN H. GUTH, Victor F. Weisskopf Professor of Physics.
CSC426 Class Material.