Chapter 2
Introduction
to the Methods
of Science
@ 2012 Wadsworth, Cengage Learning
@ 2012 Wadsworth, Cengage Learning
Topics
1.
2.
3.
4.
Naturalistic Observation
The Correlational Approach
The Experimental Method
Logic and Inference: The Detective Work of
Science
5. Scientific Observation: The Raw Data of
Science
6. Evaluating Scientific Research
7. Communication in Science
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Naturalistic Observation
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@ 2012 Wadsworth, Cengage Learning
Naturalistic Observation
• Four characteristics:
– Noninterference is of prime importance
– Emphasizes patterns
– Useful when we know little about the subject
– May not shed light on the factors that directly
influence the behavior observed
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The Correlational Approach
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@ 2012 Wadsworth, Cengage Learning
The Correlational Approach
• In correlational studies, the researcher:
– Is interested in asking whether there is an
association between two variables
– Does not attempt to establish how one variable
influences the other
• Correlation statistic: mathematical technique
used to reflect the degree of association
between two variables
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The Experimental Method
@ 2012 Wadsworth, Cengage Learning
@ 2012 Wadsworth, Cengage Learning
The Experimental Method
• All of us have used this method
• Like the child, the scientist asks, “If I do this,
what will happen?”
• To test further, the scientist asks, “Was what
happened really a result of what I did?”
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The Experimental Method (cont’d.)
• Hypothesis: idea being tested
• Experimental group
• Control group: treated exactly like the
experimental except for the factor being
studied
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The Experimental Method (cont’d.)
Table 2.1
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The Experimental Method (cont’d.)
• Operational definition: definition of crucial
terms in the hypothesis in reference to
concrete operations
• Two types of operational definitions:
– Measured: may specify both how observations are
to be made and what is to be observed and
measured
– Experimental: describes how experimental
procedures are to be followed
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The Experimental Method (cont’d.)
• Independent variable: variable that an
experimenter manipulates
• Dependent variable: aspect of the world that
the experimenter expects will be affected by
the independent variable
• “I manipulate the Independent variable”
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The Experimental Method (cont’d.)
• Treatment effect: difference in the magnitude
of the dependent variable for the control and
experimental groups
• Confounding variables: unintended
independent variables
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The Experimental Method (cont’d.)
• Clearing up confusion about causation
– An independent variable causing a change in a
dependent variable means that these two
variables reflect a consistent association
– When we use the word cause, we mean the case
in which two events are systematically connected
in a variety of situations
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The Experimental Method (cont’d.)
• The scientist can use the experimental
method in either of two ways:
– When we have no idea what the effect of the
independent variables will be
– When we have a reasonable idea about what
types of dependent variables and control groups
to use
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Logic and Inference:
The Detective Work of Science
@ 2012 Wadsworth, Cengage Learning
@ 2012 Wadsworth, Cengage Learning
Logic and Inference:
The Detective Work of Science
• Logic can help us to answer questions of
inference
• Inference: process by which we look at the
evidence available to us and then use our
powers of reasoning to reach a conclusion
• The scientist asks:
– “Given these clues, what inference can I make,
and is the inference valid?”
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Logic and Inference (cont’d.)
• Valid: true and capable of being supported
• Internal validity: internal consistency of the
experiment that allows the results to be
meaningful
• External validity: possibility of applying the
results from an internally valid experiment to
other situations and participants
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Logic and Inference (cont’d.)
• Misconception of designing “the one perfect
study”
– There are always alternative explanations
– Importance of replicating studies
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Logic and Inference (cont’d.)
• Deduction
– Process by which one moves from a general
theory to particular statements concerning data
• Induction
– Process by which one moves from a particular set
of data to a general theory or concept
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Logic and Inference (cont’d.)
Box 2.1 “Think” Squares
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Logic and Inference (cont’d.)
• Deductive reasoning
– Begin with a statement and arrives at its logical
consequences
• Inductive reasoning
– Begin with an observation and figure out a general
rule that covers it
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Table 2.2
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Logic and Inference (cont’d.)
• Falsification
– Karl Popper’s description of how science is
performed
– Science should be concerned with disproving
theories through logic based on observation
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Scientific Observation:
The Raw Data of Science
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@ 2012 Wadsworth, Cengage Learning
Scientific Observation:
The Raw Data of Science
• “If a tree fell in the middle of the forest
without anyone around, would there be any
sound?”
• In the earlier worldview, the scientist was a
passive observer
• According to modern physics, scientists do not
record events
• Scientists record their observations of events
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Scientific Observation:
The Raw Data of Science (cont’d.)
• The facts of science are relative to:
– The current notions of working scientists
– The instruments used to make observations
• Paradigm
– Current notion concerning science and accepted
methods, which encompasses a philosophical way
of seeing the world
– Shared beliefs
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Evaluating Scientific Research
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@ 2012 Wadsworth, Cengage Learning
Evaluating Scientific Research
• Four ways to ensure high quality research
– Through impartial, systematic observation using
logically sound experimental design
– Through statistical description and inference
– Through reason and logic
– By emphasizing perspective and context
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Communication in Science
@ 2012 Wadsworth, Cengage Learning
@ 2012 Wadsworth, Cengage Learning
Communication in Science
• Final product of mature science
– Communication that summarizes a conclusion
about the world and is directed to both scientists
and nonscientists
• Twofold task
– Understand how words are used in a technical
way
– In writing, define ideas as precisely as possible
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Summary
• Observation and experimentation are
important parts of science
• Correlational study determines the association
between two variables
• The two major types of validity are internal
and external
• Science reflects a history of observations of
events
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