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The Science Process
What is Science?
• Study of the natural world
• Seeks natural causes • Explains natural phenomena Dogma vs. Science
Scientific ideas are…
The Essential Believer
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Testable
Based on evidence/data
Able to be falsified
Subject to change
• tends to have unchanging beliefs
• rejects evidence that conflicts with those beliefs
• avoids dissent
• values authoritative opinions most
The Essential Scientist
•expect their hypotheses to be falsified
•search for data that can discredit hypotheses
•change hypotheses, given discrediting data
Challenges of Science
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Human Nature!
Politics
Ethics
Confounding variables
•expect scientific dissent •only evidence counts
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Confounding Variables
• Affect the variables being studied
• Influence results so that they do not reflect the actual relationship between the variables being investigated
Does A cause B? Or does B cause A? Or is C affecting A and B?
Ice cream consumption is correlated with pool drownings
Examples of Confounding Variables
• People who carry matches are more likely to get cancer
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Carrying matches  Cancer
“Correlation does not equal Causation”
Smoking
Carrying matches  Cancer
Stop global warming: become a pirate
http://irishliberty.wordpress.com/2009/10/09/more‐on‐inequality‐and‐misuse‐of‐statistics/
http://en.wikipedia.org/wiki/Flying_Spaghetti_Monster#Pirates_and_global_warming
Hypothesis: a guess about the true state, cause, or outcome of something
–capable of being tested (and falsified)
–tested using standard measurement devices
–involves factors that scientists have already agreed how to measure
Example scientific hypotheses:
1. The earth’s population is approximately 7 billion people
2. It’s 68°F outside right now
3. It’s warmer than the normal average high temp for this month
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Examples of Non‐Hypotheses:
1. God created the universe in 7 days
2. The most important environmental issue facing us today is climate change
3. Eating vegetarian would make the world a better place
How Theories are Built
Develop hypotheses
Hypotheses become a theory!
Gather data, conduct experiments
Theory: widely‐held explanation that characterizes how different factors interact to cause a major pattern in nature
Examples: • theory of relativity
• theory of evolution
• theory of plate tectonics
Types of Scientific Studies
1. surveys of people
2. observational studies
3. natural experiments 4. experiments
Results support 1 set of hypotheses, rules out all others
Surveys: people complete questionnaires or answer questions
Disadvantages:
• some people choose to participate; some don’t
• people provide their own data
• people are aware of being studied
• results may not be representative
• data are not standardized
Observational Studies:
Observe events and groups as they happen naturally in the field
• Subjects are unaware
• data are measured by researchers
Disadvantage: natural groupings contribute confounding factors and bias
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Experiments: investigator manipulates environment—establishes groups that differ only in one way • subjects placed into similar groups
• little or no confounding variables
• data measured by researchers
“They may be free of bias, but these ‘double blind’ experiments present a real technical challenge.”
• treatment imposed on 1 group, compare to untreated group
• difference in outcomes is due only to difference in treatment
• subjects, investigators unaware (blind, double‐blind
Advantages of Experiments
• can control all factors, eliminate confounding variables
• researchers can collect a large sample of individuals to study
• any difference in results between the groups must be caused by the one difference in treatment
Natural Experiments: hybrid of an observational
study and an experiment
• use natural groups that researchers can demonstrate are quite similar in all respects but the area of interest
Important Vocabulary
Controls (control groups): mini‐experiments that minimize confounding variables
• Negative control: no phenomenon is expected; ensures that there is no effect when there should be no effect. Example: Testing new fertilizer. Group that receives no fertilizer.
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Positive control: groups where a phenomenon is expected; they ensure that there is an effect when there should be an effect
Example: Group that receives already‐
established fertilizer
Placebo: simulated or ineffective treatment
Examples of Experiments
Question: Does organic produce taste better than conventional produce?
Hypothesis: People prefer the taste of organic produce over conventional produce.
Example: Group that receives simulated fertilizer containing inactive ingredients, but none of the active ingredients
• Prepare samples of organic and conventional produce
• Offer people a sample from each type
• Record their response
Things to think about:
–Sample size –Repeatability
–How to measure taste, “yummyness”
–Expectations (blind, double‐blind test)
• Establish randomized, controlled groups
• 1 group took daily multivitamin, 1 group didn’t
• Assess health for cardiovascular disease (CVD)
Results:
• Multivitamins had no effect on CVD events overall (after 7‐11 years)
Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force
Annals of Internal Medicine 17 December 2013, Vol 159, No. 12
Stephen P. Fortmann, MD; Brittany U. Burda, MPH; Caitlyn A. Senger, MPH; Jennifer S. Lin, MD, MCR; and Evelyn P. Whitlock, MD, MPH Cold Fusion
Cold fusion: hypothetical type of nuclear reaction that occurs at room temperature
• 1989 Fleischmann–Pons claimed to have done it (only explanation for excess heat)
• Also claimed to detect neutrons, tritium 5
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Jacob’s syndrome
Problems?
• Could not be replicated
• No theoretical model or explanation exists
• XYY chromosome condition • 315 patients at max‐security hospital for developmentally disabled studied
• 9/315 had XYY, more than typical population
• Current consensus: claims rejected, Pons and Fleischmann left U.S.
Initial Conclusion: extra Y chromosome causes “psychopathic personality, aberrant behavior and anti‐social conduct”
Problems with this study?
Autism and MMR Vaccine
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Sample size
Atypical population
Confounding variables
Correlation does not equal causation
• Andrew Wakefield studied 12 children
• Parents reported symptoms began soon after vaccine
• Wakefield recommended against MMR vaccine at press conference
Current consensus: only result of being XYY is increased height
Problems with this Study?
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Small sample size
Subjective data reporting
Correlation does not equal causation
Results not repeatable by others
More problems…
• Conflict of interest (patent pending on alternative vaccine)
• Accepted $435,000 from lawyers suing MMR vaccine maker
• Falsified data
• Mistreated patients/violated ethics
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Outcome…
• 10/12 authors retracted their own work • Wakefield’s paper was retracted by Lancet
• Wakefield was barred from practicing medicine in UK
• Noticed strong similarity between matching sides of the continents in fossils, geology, etc.
Theory of Continental Drift
• Alfred Wegener, b. 1880 in Germany
• Meteorologist
• 1911 noticed continents fit like jigsaw puzzle
Suggested the continents move relative to each other over the earth’s mantle (continental drift) Wegener’s idea was not well‐received
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He had observational data only
No mechanism was known
He was not a geologist
American scientists had only translations of his work, didn’t understand all of it
• Continued working on polar weather
• Died in Greenland in 1930
• 1960 new discoveries were made supporting continental drift, now part of theory of plate tectonics
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