Science Life 15: Concepts and Issues
Lecture 3: Scientific thinking and decision making
1/17/12
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Scientific thinking- an efficient way to learn about and understand the world
Hypotheses must be tested with critical experiments
Controlling variables makes an experiment powerful
Avoid the lure of pseudoscience and anecdotal observations
Scientific Method:
1. observations
2. hypothesis
3. predictions
4. experiments
5. conclusions, revise hypothesis
Q: Does it rain more on weekends?
-take data on spreadsheet
-rains 22% more on Saturdays than Mondays- WHY?- idea
-more particulate matter on weekends due to build-up all week from more driving,
enhances cloud formation and therefore rain
-where did they measure the rainfall? East coast
-in the ocean, it rains everyday equally
Scientific thinking illuminates situations in which we should change what we think.
The Critical Experiment
-putting a hypothesis to the test
-the results can decisively determine whether a hypothesis is correct
Q: Is maze running ability in mice genetic?
-test how many errors mice make in a maze over multiple times
-observation: variance in ability appears hereditary
-hypothesis: maze running is ability genetically influenced
-test: each generation, test all mice for maze-learning ability, then breed the top
20% and the bottom 20%
At the core of scientific thinking is the ability to imagine a critical experiment.
How can you increase your experiments power?
1. Randomize: subjects across control and experimental groups (ex. Paternity
study)
2. Control your study: if we want to attribute a difference between two
groups to the experimental treatment, there must be no underlying
differences between the groups. (ex. Sleep study)
3. Use a double-blind design (ex. Symmetry study)
Beware of Pseudoscience:
Scientific thinking is powerful but can be costly, time-consuming, and difficult
Cheating has an appeal
9/10 doctors recommend brand X
-how many were asked?
-how were they selected?
-alternative?
Beware of Anecdotes:
We are overly biased by observations not based on careful study and/or not
representative of the norm.
Autism is diagnosed right around the time children are vaccinated for measles,
mumps, and rubella.
-what conclusion is tempting?
Pseudoscience and anecdotal observations can be almost unbearable appealing, but
shouldnt influence our beliefs.