Transcript Scientific Method - Washington State University

Scientific Method
• Outline of the lecture
1. Clearly explain what we mean by “science”.
2. Formally introduce the Scientific Method.
3. Discuss how the scientific method applies to
social sciences in general and economics in
particular.
4. Very briefly discuss how economic methodology
has evolved.
• What do we mean by science?
– Not simply a collection of facts and concepts
– Not simply a systematic investigation
Science is a method of investigating (a subject) – a
way of knowing about the subject – that discovers
reliable knowledge about it.
– There are other methods that help us learn about
a subject, but science emphasizes the reliability of
what we learn.
– Reliable knowledge is knowledge that has a high
probability of being true because its truth has
been justified by a reliable method. (Is this
consistent with the way we do scientific tests?)
• Why is scientific knowledge reliable?
– It relies on empirical evidence
• Evidence that others can verify
• Evidence that is repeatable and/or replicable
• Contrast with hearsay, circumstantial, authoritarian
evidence
– It relies on logical reasoning
• Dispassionate (emotions don’t matter0
• Objective, not subjective
– It is skeptical
• Constant questioning of beliefs and conclusions
• Examine and reexamine the evidence, arguments and
assumptions.
• The Scientific Method in Practice
1. Ask a meaningful question about a significant
problem.
a. Must be able to state it in a way that it is possible to
answer.
b. Outside factors help shape what is meaningful
c. Should be cautious against emotion and culture
undermining the reliability of the question (postmodern thought of science as a social or cultural
construct, rather than a dispassionate analysis;
relativism)
2. Gather relevant information
a. Data and observations from previous studies, trials or
experience.
3. Propose a solution or answer (the hypothesis)
a. Informed
b. Testable
c. Predictive
4. Test the hypothesis
a. Conduct an experiment; or
b. Conduct further observations
5. Evaluate the test
a. If the hypothesis passes the test, it is corroborated
b. If it fails, it is rejected and either abandoned or
modified.
6. Construct, support or cast doubt on a theory,
and report your results.
a. A unifying self-consistent explanation of what you
observed and on other corroborating evidence.
b. Communicate your results within the context of
the existing literature
Do we have scientific facts? A scientific fact is a highly
corroborated hypothesis that has been so repeatedly
tested and for which so much reliable evidence exists
that it would be perverse or irrational to deny it.
Note, it is not stated as truth.
Scientific method in the Social Sciences
• Can the scientific method carryover to the
social sciences, or are there essential
differences that make the scientific method
inappropriate for social sciences?
– Is it that people are just more complex, and hence it
is a data problem?
– Or are the natures of the disciplines so different to
leave the methodology inappropriate?
– How hard is it to collect a preponderance of
evidence to establish a theory?
• Scientific method in the context of social
science
– Success of a theory is measured by its ability to
predict phenomenon accurately, and thus control it.
• Behavior can rarely be accurately predicted or controlled.
• But after-the-fact explanations can help guide future
actions.
• We can develop general guidelines and expectations that
are useful for both purposes
– Only that which has been rigorously corroborated is
accepted as a fact.
• But it is hard or impossible to repeat experiments or
situations.
• Is statistical control sufficient?
– The last point is what raises the real question about
scientific method in social sciences.
• Assumes in (hard) sciences paths are smooth (and
monotonic) towards facts.
• Ignores often conflicting evidence from different
experiments, or different explanations for the same
evidence
– Nutrition is an example of the former (recent studies have
changed what is accepted as good nutrition)
– The move from a geocentric to a heliocentric view of the solar
system is an example of the latter
• An economist is different from a biologist, but is the
difference in the ability to control and measure the
experiment, or in the basic phenomenon being
observed?
• Paradigm shift: A scientific revolution (or
paradigm shift) happens when scientists
encounter anomalies which cannot be
explained by the universally accepted paradigm
within which scientific progress has thereto
been made. The paradigm is not simply the
current theory, but the entire worldview in
which it exists, and all of the implications which
come with it. It is based on features of
landscape of knowledge that scientists can
identify around them. There are anomalies for
all paradigms.
• Other paradigm shifts in “hard” sciences
– Quantum mechanics replaced classical mechanics
– Darwinian natural selection replaced heritability of acquired
characteristics in evolution
• Paradigm shifts in economics
– From classical macroeconomics (MV=PQ) to Keynesian
economics
– From the Phillips curve to the long-run/short-run Phillips
curve and the idea of natural rate of unemployment
– From Keynesian economics to neo-classical macro (real
business cycle theory and the new monetarism)
– Slutsky equations (income effects)
– Parametric econometrics to non-parametrics to semiparametrics
• Changes in Economic Methodology: Three
revolutions
– Introduction of logical positivism, bringing in empirical
grounding. Friedman’s instrumentalism and
Samuelson’s mathematical modeling led this revolution.
– Rejection of the logical positivism view (led by Kuhn and
Popper) demarcating science from non-science by the
application of rules requiring replication, and moving
towards a more historical analysis.
– Rejection of normative and prescriptive economics to a
more naturalistic view of economics as an almost
biological system.
– In macroeconomics the rejection of Keynesian and growth of new
monetarism
– In microeconomics, the growth of behavioral economics.
In class exercise:
Break into groups of 3 or 4
Talk about the following observed phenomenon:
Low priced wines and liquors advertise more
than high priced wines and liquors
Within your group, find a relevant research
question, develop a hypothesis that addresses
that question, discuss a methodology (approach
and data) for testing it.