What is Science?
Science: [scientia, knowledge]
1. Knowledge gained through experience…
2. Accumulated and accepted knowledge that has
been systematized and formulated with reference
to the discovery of general truths or the operation
of general laws
3. Branch of study that is concerned with observation
and classification of facts concerned with the
physical world and its phenomena
In order to do science we have to make the
following assumptions:
• There is order to the universe (even if it is
chaotic order)
• The human mind is capable of comprehending
this order
• If conditions are the same, the results of any
study will be the same
‘God does not play dice with the universe.’
Or does She?
Science can only state what is,
not what should be.
Albert Einstein
Which of the following statements can be
tested scientifically?
• Most of the energy coming from the sun is in
the form of visible light.
• Unicorns exist.
• Shelley wrote beautiful poetry.
• The Earth was created over four billion years
ago.
• Diamond is harder than steel.
• Diamonds are more beautiful than rubies.
• The claim is sometimes made that the
scientific method produces closer and
closer approximations to "reality."
• Is this a scientific statement? Why or
why not?
The Scientific Method
Scientists develop their knowledge by
observation and experimentation
Observation is used in two ways:
1. Inductive reasoning - discovering general principles
by the careful examination of specific cases. Here
the scientist organizes data (facts) into categories
and asks what they have in common
2. Deductive reasoning starts with general cases and
proceeds to specific cases - it makes relationships
clearer and allows predictions to be made
Scientific knowledge advances by a
method known as "strong inference"
Strong inference works as follows:
1. Make an observation or measurement
2. State an hypothesis
3. Test the hypothesis
4. Publish the results
5. Restate the hypothesis, test again
Observation
Semmelweis (1856), observed in hospitals in
Vienna, that 5X the number of women died during
childbirth if they were attended by a physician as
compared to being attended by a nurse
(“childbed fever”).
One of his colleagues died of childbed fever after
cutting his hand with a scalpel during an
autopsy.
Doctors are often doing autopsies before
attending to childbirths.
Observation
(inductive reasoning)
Hypothesis
Semmelweis hypothesized that “cadaveric
matter” was transmitted from the autopsy
room to the delivery room.
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
Washing hands would eliminate the
cadaveric matter and reduce childbed
fever.
null hypothesis vs.
alternative hypothesis
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
Experiment
Observation
Experimental design
•controls
•dependent variable
(what’s affected)
•independent variable
(what’s the “cause”)
•predicted data (must be
able to differentiate
between null and
alternative hypotheses)
correlation ≠ causation
correlation ≠ causation
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
[Experiment]
Experiment
Observation
Analysis
(Observation = Prediction?)
Childbed fever deaths absent
when physicians washed
their hands
Childbed fever deaths absent when physicians
washed their hands
Semmelweis
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
[Experiment]
Experiment
Observation
Analysis
(Observation = Prediction?)
Conclusion
Transmission of
cadaveric matter causes
childbed fever
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
[Experiment]
Experiment
Observation
Analysis
(Observation = Prediction?)
Conclusion
What other hypotheses
could be made from the
conclusion?
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
[Experiment]
Experiment
Observation
Analysis
(Observation = Prediction?)
Conclusion
What would you
predict from your
hypothesis?
How would you
test it experimentally?
Observation
(inductive reasoning)
Hypothesis
(Deductive
Reasoning)
Prediction
[Experiment]
Experiment
Observation
Analysis
(Observation = Prediction?)
Conclusion
Theory
Law
Fact
Scientific method Initial Observation
reasoning?
is a repetitive
process that leads Hypothesis
to the building
of theories
New
Hypothesis
Experiment
New
Experiment
Observation/
Data Analysis
New
Observation
Hypothesis not Supported
Interpretation
Final Hypothesis Supported
Theory
Preconceptions can influence scientific method
Identifying
Patterns
Observations
Experimentation
Data
Preconceptions
Hypothesis
Prediction
For childbed fever: “vapors”, spontaneous
generation, women as “weak”
accumulated
scientific data
Theories in science
build from the
accumulation of multiple
investigative efforts
formulation of
hypothesis
observation and
experimentation
new data
conclusions
1
2
3
etc
theory
communicable disease
Summary
• The scientific method is in essence a process
of observing natural phenomena which leads
to the asking of questions about those
phenomena which leads to the offering of
explanations that can subsequently be tested
Mystery Box
• Hand out mystery boxes
• Do hypothesis testing exercise