the Scientific Method and the Scientist
"Equipped
with his five senses,
man explores
the Universe around him
and calls the adventure Science."
Edwin P.
Hubble
astronomer - 1948
A
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Gk:
Bios
= life
Logy
= study of
the term
biology was coined by
Gottfried R.
Treviranus in 1802.
______________________________________________________________________
Physics
is the study of
atomic particles that interact by
a relatively simple set of rules that may be distilled
into predictive formulas.
Chemistry is a more complicated application of
physics & its rules,
Biology, then could be a
more complicated application of chemistry,
which also might be reducible to predictive physical formulas.
but as we shall learn,
Biology's rules are messy and its infinite
molecular interactions are almost
impossible to faithfully predict.
Scientific Theories have 2 components:
1.
one component describes
PATTERNs
observed in the natural world
2.
other component identifies a
PROCESS
or MECHANISM
responsible for the pattern
SCIENTIFIC METHOD*
read this
......is a manner for
investigating
Nature
it's the methodology
by which scientists, collectively and over time, attempt to construct
an accurate, reliable,
consistent, and non-biased representation of the
natural world.
a
way of investigating the things (patterns)
we observe around us...
a way of
recording...
the
mechanisms
(laws)
that govern our physical world...
a careful observation &
measurement of patterns of living things & their
processes...
it employs
rigorous methodology
and
it devises
experiments to validate observations...
Some
THOUGHTS and
QUOTATIONS...
what the
Scientific Method
is... & about who is a
Scientist
The scientific method was initiated by the Greek
philosophers [2600 years ago].
Thales
(ca 590 b.c.) is considered the founder of the scientific method...
The prime question asked was..
"what differentiates living from non-living".
"
If we admit a priori that science is just the acquisition of knowledge, that
is, the
building an
inventory of all observable
phenomena
in a given disciplinary domain,
then, obviously,
any science
(may be called)
empirical."
Rene Thom, 1989
A scientist is one who works in the
trenches, seeking correct answers to a particular
problem,
checking exhaustively for exceptions, guarding against mistakes and
preconceptions of an outcome, and
avoiding personal bias.
Scientist's do not need a license to ply their trade. Science is a field
that
depends almost
completely on the honor and integrity of its individuals.
"Science
is what scientists do, and there are
as
many scientific methods as there
are individual scientists.
The scientific method is what working scientists do,
not what other people do or even what they themselves may say about it."
Percy
Bridgman, "On scientific method," in
Reflections of a Physicist,
New York: Philosophical Library, 1955
Phrases by Mallery
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SCIENTIFIC METHOD..... commonly involves a number of steps
1.
Observations
.... and
description of a phenomenon or group of phenomena.
i.e., a gathering of
the data...
from
previous studies
or directly...
observation:
Bil 150students sitting in the
back of the lecture hall, often fall asleep?
Begin to ask a Question:
about the how's & why's of the things you
observe.
in scientific method: questions must be
framed in
measurable terms.
Look for Answers to Your
Question:
others may have asked & answered the same
type of question.
do literature searches: textbooks, journal &
internet articles...
reading other people's findings may lead to more interesting questions;
and help define or modify your question better.
pose question: Does sitting in warm air at top of lecture
hall promotes student sleep?
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-
2. Postulating a Premise.... formulating an explanation (testable hypothesis) of phenomena
the posing of a critical and experimentally testable question -
Does sitting in back of Bil 150 classroom promote sleep?Develop possible explanations:
Formulating a Hypothesis*.... to predict the existence of other phenomena,
or to predict quantitatively the results of new observations- a tentative or possible explanation,
a proposed explanation for a phenomena that is experimentally testable...- sitting in the back of the classroom keeps a student
- out of reach of instructor & its warm & cozy.
-
one must state the
testable hypothesis as precisely as possible
and must list the expected predictions that the hypothesis makes...
...often involves critical analysis & critical thinking -
...may also suggest an alternative hypotheses -
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-
4. Experimental Predictions... making a prediction that can be tested - states results that may be expected
- from observations and/or from experimental tests
- moving a student from back to the front of the room can prevent sleep.
-
Design an Experiment to test your Hypothesis:
requires experience, creativity, and sense of what is practical.
read methods published by others - modify them to your purpose,
brainstorm with others - different perspectives are helpful,
you may be limited by equipment availability, costs, and time. -
experiments are
supposed to test a premise...
moving one of two students to front will keep that student AWAKE ???
experiments are best designed to DISPROVE, not to prove a hypothesis.
It is often said in science that theories can never be proved, only disproved.
There is always the possibility that a new observation or a new experiment
will conflict with a long-standing theory.
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a Hypothesis
can be refuted
(proven wrong) or falsified,
but a hypothesis
by no means
can be proven right;
evidence can be collected to
provide support
for a hypothesis...
thus,
there is often
no proof
in science, only
'disproof':
an example...
Luis
Alvarez (geophysicist) investigated
assassination
of JFK.
Premise:
backwards motion of JFK's head as fatal
bullet struck proves at
least one shot must have come
from front (dual shooter idea),
since a shot from behind would only push head forward [Zapruder
film].
Hypothesis: "reflex of head
requires a shot to have been fired from the front".
Experimental Alvarez
showed
backward snap of head is consistent with shot from behind
disproof:
(laws of physics established a head can recoil
backwards).
Conclusion: experiment
does Not Prove shot was from
behind,
but does Disprove presumption that a
shot must have come from front.
when scientists publish they never say
"results prove..."
but rather
"results suggest..."
or
"results provide support for..."
hallmark
of the scientific method is...
DESIGNING an
Experiment
Purpose of an EXPERIMENT...
to
disprove a hypothesis or
to evaluate an
alternative hypothesis
experiments should meet certain criteria:
unbiased...
define the
variables
(see
auxin
experiment below)...
dependent variables: such as - number of parts, stem length, etc...
measurable & observable things;
the variable modified by treatment
independent variable: only one variable to be manipulated, which may change
time, height, weight, age, sex, amount of hormone, etc...,
the treatment
controlled variables: those kept
constant and not allowed to change
all experiments must have a control...
standard for
comparison
(a challenge)
example:
relationship of
plant growth hormone
auxin
to plant growth:
dependent variable: stem length (growth).
independent variable: auxin amount
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and
controlled variables: temp, humidity,
day length, amount of fertilizer.
a big
part of experimental design is
materials & methods
(the procedures)
based
on previous published works, collegial suggestions, intuition,
etc...
if auxin is added to dwarf plants
will stems grow to normal height?
our experiments ought to include:
1.
control: negative control:
dwarf plants NOT given auxin
positive control: normal plants NOT
given auxin
*
2. proper concentration levels:
should not be too low (no effect
detected) nor
too high (toxic);
should be within physiological parameters
of living cells
3.
must be
recordable:
quantitatively
measureable as length (mm)
4. must be
replicable... redo
several times, to be statistically valid
experiments
ought to show consistent results
again and again, from test to test
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Protocols &
Terminology of the Scientific Methodology...
one often makes
predictions about outcome of an
experiment:
that
involves using...
Hypothetico-Deductive Thinking... which
includes the formulation of an HYPOTHESIS,
(which is a tentative answer to a question) and doing experiments
from which
may deduce a general answer to the hypothesis... often
involves
critical thinking...
nothing is accepted as fact, unless it is experimentally
demonstrable
deductive
reasoning...
if...then deductive logic
if
all birds have feathered wings,
and
a robin is a bird,
then
robins have feathered
wings.
predictions
for our auxin experiment:
negative control: dwarf plants treated
with water = remain short (dwarf)
positive control: normal plants treated
with water = normal height
test treatment: dwarf plants treated
with auxin = grow taller (normal)
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Hypothetico-deductive
methodology of scientific method
also includes:
inductive
reasoning...
is the ability to deduce intuitive/creative principles...
objects fall to ground when dropped
thus,
a force
must act on the object... [gravity]
is
cumulative...
- results from
earlier studies become initial
observations of new studies
- everything that science "knows"
- even long established theories -
are subject to reexamination as new
information is collected.
- no
endeavor of humankind rivals
Science
in its
incremental progress
toward a more complete understanding of the observable world
"The beauty of science is that all important
discoveries are made
by building on the discoveries of others".
JC Venter...A Life Decoded,
2007
shows
adaptability...
-
not all experiments are clear
cut, scientific results must fit into known facts:
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" all scientific knowledge is tentative, and open to challenge"
cm
The Collection & Interpretation of Data...
often draws upon previously known knowledge...
scientists fit new
knowledge into framework of what they already know...
observations and measurements
must always use
same criteria...
plant height always
measured from pot rim to shoot tip
variability must be
estimated...
statistical analysis:
some common statistical tests include...
t-test
- compares the means of
two groups
ANOVA
- compares means of three
(3) or more groups
chi square
- compares how closely
the observed or measured data
is to the expected results (ex: genetic crosses)
µ
Progress in science often depends upon
new techniques,
new discoveries,
and new ideas, probably in that order.
-
Sydney Brenner, 2002 Nobel Prize
winner
"Although
concepts and
ideas occupy a central
place in the grand sweep of our under-
standing of the nature of the world around us, it is a mistake to
imagine that they play a
greater role than
tools
and
techniques
in achieving scientific progress.
Few scientific revolutions are concept driven."
[re:
HGP].... John M.
Thomas, 1994.
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Organizing Data... raw data
is often expressed in tables and
figures
tables: often used to emphasize numbers themselves, rather than a trend
figures: graphs show
trends;
pictures, photos, diagrams are
visuals.
line graphs - show effect of
independent variable (X-axis) on
the dependent (measured) variable
(Y-axis)
bar graphs - compare sets of data that
may be discontinuous
i.e., maybe different groups
the best way to display your data often depends on what you want to
show
Examples*:
aim is
to show maximum growth rate is reached after several weeks
some fun experiments
-
The Twinkie Project...
[Rice University finals Week 1995]
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Mastering Biology Concept Activity -
1.3 -
An introduction to Graphing*.
It's easy to formulate an
initial hypothesis...
It's hard to make a connection
between cause and effect.
Draw a conclusion...
if experimental
outcomes match your predictions,
then your hypothesis is supported,
if not, then your hypothesis is
negated.
Do your results agree with findings of other?
if not, do you know why not [different methods or species?]
Experimental
Results are a
tool: provide a sense of
direction to experiments
do NOT let predictions affect your objectivity
do NOT make results fit your predictions (bias)
you may modify your hypothesis to better fit the observed results...
modifications of a hypothesis help scientists gain assurance
that their explanations may be valid.
Negative results are often more important than
positive ones:
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Campbell - Concept Activity
- Investigations -
Chapter 1
1.4 -
How Do Environmental Changes Affect a Population*
1.5 -
How Does Acid Precipitation affect Trees*
- maybe you can formulate or substantiate a Theory...
- ...the set
of rules & procedures governing what we have observed
a THEORY is... a hypothesis that has stood the experimental test of time
if experiments always bear out a hypothesis, it might be regarded as a THEORY or LAW of natureIn many scientific disciplines, the words "hypothesis", "theory", and "law" can have different
connotations in relation to the stage of acceptance or knowledge about a group of phenomena.
A hypothesis is a limited statement regarding cause and effect in specific situations;
it also refers to our state of knowledge before experimental work has been performed
Example: you discover that your car will not start. You may hypothesize...
"My car doesn't work, because the battery is dead." a first hypothesis to test*.A scientific theory or law represents a hypothesis, or a group of related hypotheses,
which has been confirmed through repeated experimental tests over a long period of time.
"The
philosopher ('scientist') proposes a solution in the form of a 'hypothesis',
as a revelation of 'truth'
that has been tested experimentally, again and again".
P. Haezrahi, 1970 paraphrased
by chm 2002
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-
the scientific method
has limitations...
- science does not deal with hypotheses
- that are NOT EXPERIMENTALLY TESTABLE...
How many of you believe there is life elsewhere in the Universe ?*
IRONIC
SCIENCE...
(non-testable theories, but
which are scientifically based)
Is there life elsewhere in
the Universe
?
Global
warming - its causes
? ...fossil
fuels, deforestation, agriculture?
Nuclear winter or
meteor
(...a cause dinosaurs mass extinctions? ice ages?)
Mount
St.
Helens,
Gulf War...
Earth-on-fire?
Complexity &
chaos
theory?
makes
it difficult to predict exactly
what is going to happen at any given time, in the present or the future.
chaos theory deals with the behavior of
nonlinear
dynamical systems
that are characterized
by sensitivity to initial conditions. Examples include the
atmosphere,
the solar system,
plate tectonics,
turbulent
fluids, economies, and population growth.
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ERROR in scientific experiments happens...
& can have have several sources.
1. There is error
intrinsic to the instruments used for measurements
--> random error.
2. There is
non-random or systematic
error, due to factors which may bias the results.
No measurement, and therefore no experiment, can be perfectly precise...
A. Human error:
failure to follow procedures, failure to use the equipment properly,
failure to prepare solution correctly, measurements made by 2 researchers,
simple arithmetic errors, etc...
B. Another common mistake is to rule out or
ignore data which do not
support
the hypothesis... Humans have psychological tendency to find "something
wrong",
with data, which does not support their hypotheses.
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ERROR
cont.
C. a scientist's
personal bias can effect the outcome of an experiment...
most fundamental error is to mistake the
hypothesis for an explanation of a
phenomenon, without performing experimental tests. Sometimes
"common sense"
and "logic" can tempt us into believing
that no test is needed.
...teacher can hit student in front to keep awake
[bias]
Bias can be overcome... via
open communication among members of the
scientific
community because experimental tests are repeated by different
scientists...
using different types of experimental setups.
Sharing your results...
the "PUBLISH or
PERISH" Rule
1. in a paper in a referred (peer-reviewed)
journal publication +
Open Access
2. at a poster session at a
scientific meeting
3. via seminars at scientific
meetings or symposia
-
Over a period spanning a variety of experimental tests (usually several years),
a consensus develops in scientific community as to which experimental results
have stood the test of time and become ----> THEORY. - the word THEORY...
to scientist the word THEORY means established FACT or TRUTH
to lay person (philosopher) the word THEORY may mean...
a speculation, a guess, an unknown, or a lack of knowledge
- Scientific Insanity: doing the same experiment over & over,
-
but expecting a different result each time
If Science is what scientists do the What Makes a Scientist*...
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*
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Last Update -
09/03/2009