Transcript Chapter 1

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A modified version of the powerpoint for
Biology for a
Changing World
SECOND EDITION
Lecture PowerPoint
CHAPTER 1
Process of Science
Probably not approved of by these guys  Copyright © 2014 by W. H. Freeman and Company
Major topics
•Science & Scientific Method
•Characteristics and organization of living
things
•Biology = Bio (“life”) + logy (“study of”)
•Scientific study of life
Important themes
(You should understand
this stuff for the test)
1. scientific method: how we test hypotheses
2. Good science vs. bad science
3. How much should you trust media reports of
scientific studies? (hint: learn to read carefully)
4. Know real world examples of scientific method in
clinical trials/human health?
What is science?
• A method to answer questions
• use observations & experiments to make
evidence-based conclusions
• A way of knowing
This guy’s definition
“strictly adhering to a simple set of rules”
1.
2.
3.
4.
5.
Test ideas by experiment and observation
Build on the ideas that pass the test
Reject the ones that fail
Follow the evidence wherever it leads
Question everything
Summary do we need to know this?
•How we try to understand natural world
a. What we can observe or measure the effects
of
b. There are things science cannot answer (pg. 4
& 13)
•Goals – logical, objective, based on
evidence
Characteristics of
Scientific Knowledge
•Natural world – what we detect, observe or
measure
•Evidence based – experiments or observation
•Peer review and independent validation
•Open to evidence based challenge by anyone
New evidence can change everything
•Self correcting process
The Bad News
Scientists are
human.
•Mistakes
•Fraud
•Cheating
How can you evaluate the evidence in
media reports of scientific studies?
Extraordinary Claims need
Extraordinary proof 
Is the claim in the news what the
researcher actually said 
Who paid for the research? How
did it affect the researchers 
http://blogs.telegraph.co.uk/news/tomchiversscience/100252700/when-drugcompanies-dont-publish-trials-real-people-die/
http://www.nytimes.com/2013/06/30/business/breaking-the-seal-on-drug-research.html
How can you evaluate the evidence in
media reports of scientific studies?
Too many Weasel Words 
Tests with small samples
usually don’t prove anything 
How can you evaluate the evidence in
media reports of scientific studies?
Test subjects must be like
population
Control: were results due to
what you were testing?
Do scientists’ knowledge affect
the results?
How can you evaluate the evidence in
media reports of scientific studies?
use ALL the data, not just the
results you like
Can other people get same
results if they repeat test
Ongoing….not a one time thing
(all ideas open to change when
new evidence is found)
What methods were used?
• Ask: Was the science performed properly?
Bad methods = bad data = bad conclusions
What methods were used?
• Use best evidence
available
• Ask: Was the science
performed properly?
How do scientists draw conclusions?
Best explanation based on the evidence we have RIGHT NOW
• Conclusion may be
modified in the future
• Science is a
never-ending
process
The Peer Review Problem
Scientific mistakes and fraud can only be detected if
people
a) See errors in the methodology of the research
b) Try to duplicate the experiment without those
mistakes (have evidence it doesn’t work as described)
This doesn’t always happen
(if reported results match everyone’s expectations,
they probably won’t be checked)
What we
want 
What often
happens 
About that peer review….
http://phylogenomics.blogspot.com/2012/02/2010-arsenic-found-in-dna-2012-we-never.html
Peer review should not be considered a thumbs up / thumbs down process as
you are suggesting here. And it should not be considered a one time event. It
should be considered a continuous process and a sliding scale. Some things
that get through the normal peer review process for papers are end up being
retracted and many things that are presented prior to traditional peer review are
fundamental new insights. Scientific results can be evaluated before, during
and after the review that happens for a publication. Scientists do this all the
time already - at conferences - in hallways - in lab meetings - on the phone - on
skype - on twitter - at arXiv - in the shower - in classes - in letters - and so on. It
is actually a disservice to science to annoint "peer review" as applied at some
journals into something it is not.
How to do GOOD science
Be skeptical about results (even your own!!)
If results seem AMAZING
• Check your equipment
• Talk to another scientist before running to
the press.
– Can they find problems w/ your experiment
– Do they think your results seem reasonable
•
Key - Must try to prove false what you believe is true
Scientific Method
•A description of the scientific thought process
•Not a ridged list of steps that all scientists must use
all the time
example: like learning to waterski
Steps in the Scientific Method
•Observation
•Hypothesis
•Making a prediction
•Testing
fish dying near factory
factory chemicals kill fish
if true, chemicals kill fish in lab
Same water conditions for all
(pH, temp, oxygenconcentration)
Control Group
no change in experimental variable
why?
Ensure results due to exp. variable
•Results – support hypothesis?
Science is a process:
make an observation
• Start with an
interesting,
informal
observation
• Often unreliable,
untested
• Anecdotal
evidence
Science is a process:
formulate a testable question
• Use observation to devise a
question
“ Does coffee help improve
mental performance?”
Science is a process:
studying previous research
• Read relevant literature
• See current information on
the subject of interest
• Study peer-reveiwed
scientific literature
• What do reputable experts
in field say?
Science is a process:
studying previous research
• Peer review: review of an article by experts before
publication
• The plan: make sure authors correctly designed & interpreted
their study
• weeds out sloppy research
Science is a process:
forming scientific hypotheses
• use information to formulate a
scientific hypothesis
• a testable and falsifiable
explanation for a scientific
observation or question
“Caffeinated coffee improves
memory.”
Science is a process:
forming scientific hypotheses
testable : supported or rejected by carefully
designed experiments or nonexperimental
studies
falsifiable: can be ruled out by data
If-then predictions: if hypothesis is true, then…
Science is a process:
forming scientific hypotheses
• Not all explanations are scientific hypotheses
• An explanation that cannot be tested or is
NOT a scientific explanation
Science is a process:
forming scientific hypotheses
• A hypothesis is never proven
• If false, it is rejected and no longer considered a
possible answer to the original question
• If the data support the hypothesis, it will be accepted
until more testing and new evidence show otherwise
“No amount of experimentation can ever
prove me right; a single experiment can
prove me wrong”
- Albert Einstein
Science is a process: experimentation
• Hypotheses can be
tested using
experimentation
• An experiment is a
carefully designed
test
• The results of an
experiment either
support or rule out a
hypothesis
Experiment: how to test hypothesis
example: measure the effect of drinking coffee
experimental group:
experiences the experimental
intervention or manipulation
control group: experiences
no experimental intervention  don’t alter “independent variable”
or manipulation
Basis for comparison
2 groups in experiment
• The control group receives a placebo
A placebo is a
fake treatment
similar to
experience of
experimental
groups
Variables in experiment
• independent variable  what we change
• dependent variable the results we measure
• Analyzed in both the experimental and control
groups
Science should be based on evidence
• our conclusions should be based on results
that we measure
How can we be sure conclusions are right?
NEVER 100% sure
We get more confident if other scientists repeat
test and get same results
Math: how certain we can be
• Sample size is
important
• It is the number of
experimental
subjects or the
number of times an
experiment is
repeated
Big sample:
Results are
meaningful
chance
Small sample:
Results could be
chance
Science is a process: drawing conclusions
The larger the sample
size, the more likely the
results will have
statistical significance.
Statistical significance is a
measure of confidence that the
results obtained are “real,” rather
than due to random chance.
Publication: getting info out there
Experimental results are published in peerreviewed journals.
Traditional
Print journal
Open access
Print journal
“The widely held notion that high-impact
publications determine who gets academic
jobs, grants and tenure is wrong. Stop using it
as an excuse.”
http://www.motherjones.com/media/2013/09/michael-eisen-plos-open-access-aaron-swartz
The book is wrong!!! (Yes, this is nitpicking)
A hypothesis may eventually be considered a
will never become scientific theory.
A theory is an explanation of the natural world that is strongly supported and widely
accepted by scientists
Support comes from repeated testing over several decades
Far greater confidence in this explanation than in an educated guess
One hypothesis does not become a theory by itself, but many
hypothesis on a subject can be used to form a theory.
Theories are more general (applies to many situations)
Science is a process: scientific theory
Science without experiments????
• Some questions cannot be tested through
controlled experiments Astronomers can’t blow up a star
• Use observation to find
patterns and help
answer questions
• Epidemiology is the
study of patterns of
disease in populations
 Lucky star
Science is a process: finding patterns
• Observing patterns can show a consistent relationship
or link, between variables
• Correlation
• Correlation between two variables does not prove
that one variable causes the other
Fewer coffee drinkers had Parkinson disease
But: Correlation is not causation! Does not prove!!!!!
Correlation ≠ cause
Correlation ≠ cause
Science is a process
• Use a known correlation to design a controlled
experimental study
• Conduct a randomized clinical trial
• Randomly chosen subjects used in control and
experimental groups to test an independent
variable
Evaluating scientific information
Data are often very complex and the public
often receives them as isolated media headlines
“linked to”
Summary
• Science = process: use studies to answer
questions or test hypotheses.
• observational studies or experiment results
can support or rule out a hypothesis.
• NEVER can have 100% certainty
• future studies: new evidence may change our
minds
Extra stuff that is on 1st test
•
•
•
•
•
•
•
Properties of Life (pg. 24-25)
Viruses (pg. 38)
Taxonomy (382-384)
Heterotrophs/autotrophs – 105
Natural selection (310-312)
Endosymbiosis (57, 68-71)
Autotrophs, heterotroph, photo synthesis &
chemosynthesis (p.398)
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