“The urgency in which our nation needs to address issues related to sustainability, such as energy and climate change, is amplified by the fact that for the first time since the Pliocene, CO2 levels have reached 400 ppm (March 2013)…Therefore we look to our young people to be leaders and stewards of Earth’s many systems, knowing that 80% of the jobs you will have in the future do not yet exist. Presently, 80% of the fastest growing occupations in the U.S. require STEM adequacy, but the U.S. is currently not graduating enough students who are able to fulfill this growing need.”

…lots and lots and lots of math.

2/18/1996

What is the scientific method? What does the scientific method

assume? Does the scientific method work? What is not a scientific argument? What is a bias?

1. Observe an event.2. Develop a model (or hypothesis) which

makes a prediction.3. Test the prediction.4. Collect data5. Revise the hypothesis.6. Repeat as needed.7. Communicate results- A successful

hypothesis becomes a Scientific Theory.

model

test

Scientific Method

High Cholesterol

Observation Patient has high cholesterol

Hypothesis (prediction)

Certain chemicals may dissolve cholesterol deposits.

Test Give 100 patients these chemicals, give 100 patients placebo.

Observe result Same number lower their cholesterol as placebo patients.

Revise hypothesis?

Try different combo of chemicals.

New test? Re-run medical test. Observe results.

Scientific Theory

Lipitor reduces cholesterol.

Scientific Method Car Repair

Observation Engine won’t turn over.

Hypothesis (prediction)

Predict battery is dead.

Test Replace battery.

Observe result Engine now turns over.

Revise hypothesis? Not needed.

New test? Not needed.

Scientific Theory Cars won’t work without a fully charged battery.

Independent Variable= “what do I change?”

Dependent Variable= “what is observed, effected, or measured by the change?”

Control= “what stays the same?”

So: a theory is a highly successful hypothesis.Theories make predictions and can be

tested. Any scientific theory is subject to

change as our ability to make tests, or make observations of a test’s results, improves with time.Ex: The Cell Theory was revised because of

advancements in technology

A successful theory is repeatable.By you.By anyone.

Assumes:Objective reality

We all see the same world.Constant Laws of Nature

What happens here, happens there. What happened yesterday will happen

tomorrow.

Law= readily observable fact Doesn’t needed to be tested

Ex: The Law of GravityTheories won’t “grow up” to become a law

Make no predictions Un-testable Can’t be falsified

What does this sound like?

Car won’t work? Aliens drained the battery.

Car won’t work? Better sacrifice a goat to appease the Gods.

Spaghetti is bland? At the instant of tasting, tongue is transported to alternate dimension where all flavors are rendered nullified. Happens instantaneously.

Objectivity is the key to good science.To be objective, experiments need to be

designed and conducted in a way that does not introduce bias into the study.

Science:Makes predictionsCan be testedCan be falsified

Bias= A prejudiced presentation of materialA consistent error in estimating a value

Two main types of bias:Sampling biasMeasurement Bias

Sample = A group of units selected to be “measured” from a larger group (the population).

Sampling bias = introduced when the sample used is not representative of the population or inappropriate for the question asked.

Is the method of data collection chosen in such a way that data collected will best match reality?

Evaluate the technique:Measurements taken accurately No additions to the environment that will

influence resultsExperiment designed to isolate the effect

of multiple factors

Use a random sample= every individual has an equal likelihood of being chosen.Eenie, meenie, miney, mo…

Limit the question asked to the specific group sampled

Sample size: Is the sample big enough to get a good

average size? Selection of sample:

Does the composition of the sample reflect the composition of the population? Factors such as location, age, gender, ethnicity,

nationality, and living environment can affect the data gathered

Independent duplication = Two or more scientists from different institutions investigate the same question separately and get similar results.

Peer-reviewed journal = A journal that publishes articles only after they have been checked for quality by several expert, objective scientists from different institutions.

Language“Scientifically-proven”

* Science does not seek to prove, but to disproveEmotional appeals

Data should convince you, NOT words!

Appropriate data reported to back conclusionsSamples and measurements are

appropriate for the conclusion presentedMultiple factors properly accounted for to

justify the interpretation of the data

Data sourceUniversity ResearchCorporate ResearchGovernment ResearchResearch by Special Interest Groups

All organizations produce unbiased data. However, it is important to understand the organization’s motivation to be able to identify potential bias. In some situations, the need to promote special interests or make profits may lead to bias.

Number (%) of Reviews

 Article Conclusion Tobacco Affiliated Authors (n=31)

Non-Tobacco Affiliated Authors (n=75)

Passive smoking harmful 2 (6%) 65 (87%)

Passive smoking not harmful 29 (94%) 10 (13%)

Significance Χ2=60.69; P<.001

Barnes, Deborah E. 1998. Why review articles on the health effects of passive smoking reach different

conclusions. JAMA. 279(19): 1566-1570.

Investigations of Passive Smoking Harm: Relationship between the article

conclusions & author affiliations

Good science depends on a well-designed experiment that minimizes bias by using the appropriate:Sample sizeSample selection Measurement techniques

(*for the question being investigated*)