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Biology for aChanging World

SECOND EDITION

Lecture PowerPointCHAPTER 1

Process of Science

Probably not approved of by these guys Copyright © 2014 by W. H. Freeman and Company

A modified version of the powerpoint for

Major topics

•Science & Scientific Method•Characteristics and organization of living things•Biology = Bio (“life”) + logy (“study of”)

•Scientific study of life

Important themes

1. scientific method: how we test hypotheses2. Good science vs. bad science3. 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?

(You should understand this stuff for the test)

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. Test ideas by experiment and observation

2. Build on the ideas that pass the test

3. Reject the ones that fail

4. Follow the evidence wherever it leads

5. Question everything

Summary do we need to know this?

•How we try to understand natural worlda. 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

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

How can you evaluate the evidence in media reports of scientific studies?

http://www.nytimes.com/2013/06/30/business/breaking-the-seal-on-drug-research.html

http://blogs.telegraph.co.uk/news/tomchiversscience/100252700/when-drug-companies-dont-publish-trials-real-people-die/

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)

How can you evaluate the evidence in media reports of scientific studies?

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?

• Conclusion may be modified in the future

• Science is a never-ending process

Best explanation based on the evidence we have RIGHT NOW

The Peer Review Problem

Scientific mistakes and fraud can only be detected if peoplea) See errors in the methodology of the researchb) 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 fish dying near factory•Hypothesis factory chemicals kill fish•Making a prediction if true, chemicals kill fish in lab•Testing

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 hypothesisexample: measure the effect of drinking coffee

experimental group: experiences the experimental intervention or manipulation

control group: experiences no experimental intervention or manipulation

Basis for comparison

don’t alter “independent variable”

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% sureWe 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

Small sample: Results could be chance

Big sample: Results are meaningful 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 thereExperimental results are published in peer-reviewed journals.

TraditionalPrint journal

Open accessPrint journal

http://www.motherjones.com/media/2013/09/michael-eisen-plos-open-access-aaron-swartz

“The widely held notion that high-impact publications determine who gets academic jobs, grants and tenure is wrong. Stop using it as an excuse.”

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 decadesFar 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

• Use observation to find patterns and help answer questions

• Epidemiology is the study of patterns of disease in populations

Astronomers can’t blow up a star

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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