Experimental Design and the
Scientific Method
Warm-up (8-27-14)
• Write down what you think experimental
design means
• Why do you think experimental design is
important?
• Can you perform an experiment without
thinking of “experimental design”?
Warm-up (8-28-14)
• What are the steps of the scientific method?
• Why does slope matter in science?
• Give an example of a poorly designed
experiment.
Outline
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Objectives
Why do I care?
Slope Review
What is Experimental Design?
Purpose
Scientific Method
Steps
Objectives
• Explain the purpose of experimental design
and why it is important
• Determine the difference between accuracy
and precision
• Explain the importance of the scientific
method and why peer review is significant
Why Do I Care?
• Experimental design determines the validity of
the results presented
• Determines whether or not you can trust the
experiment
• Scientific Method is the basis for all scientific
thinking and questioning
Slope Review
• Y=mx+b
– What do these random letters mean??
• Why do we need slope?
– The slope of a line is a rate of change and is
represented by m.
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• When a line passes through the points (x1,
y1) and (x2, y2), the slope is m = ???
What is Experimental Design?
What is the PURPOSE of Experimental
Design?
• Randomize
– Even out effects we cannot control
– Ensure equal chance to all possibilities
• Control
– Make sure we only get results for what we want
What is the PURPOSE of Experimental
Design?
• Replicate
– Get as many replicates (repeats) as possible.
– Results for a single subject might not be accurate. (No
one is perfect on the first try all of the time.)
• Block
– Get rid of things we don’t want to study and that we
can’t control
• Best Experiments Are??
• The best experiments are usually randomized,
comparative, double-blind, and placebocontrolled.
Parts of Experimental Design
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Independent Variable
Dependent Variable
Hypothesis
Control
Replication
Purpose
Experimental Group(s)
Control Group
Constants
Let’s Try It!
Experimental Design Practice (Remember our
check list!)
• What do we need to include / What questions
do we have to answer?
Superstitions
• If you blow out all the candles on your
birthday cake with the first puff you will get
your wish.
You Try It!
• Complete the activity with your table groups. I
will number your tables!
• Make sure that you are each writing down the
answers on your own paper.
• You will need these examples as a reference!
• Superstitions used for practice with experimental design.
1. An apple a day keeps the doctor away.
2. Eating chocolate causes zits.
3. Shaving your legs makes the hair grow back more densely.
4. A knife placed under the bed during childbirth will ease the pain
of labor.
5. Drinking coffee will stunt a child’s growth.
6. If you swim right after eating, you will get cramps.
7. If you catch a falling leaf on the first day of autumn, you will not
catch a cold all winter.
8. If you go outside when your head is wet, you’ll catch a cold.
9. A red ribbon placed on a child who has been sick will keep the
illness from returning.
10. A half onion placed under the bed of a sick person will reduce the
fever.
11. Feed a cold, starve a fever.
12. Break a mirror and you will have seven years of bad luck.
13. Spit on a new bat before using it for the first time to make it lucky.
Warm-up (8-29-14)
• Without experimental design and the
scientific method, would there be valid
experiments? What do you think?
• https://www.youtube.com/watch?v=eA86dYxr
g4Q
Outline
• Objectives
• Accuracy and precision
• Scientific method
Objectives
• Determine the difference between accuracy
and precision
• Explain the importance of the scientific
method and why peer review is significant
• Determine the importance of peer review and
practice using peer review to evaluate the
work of scientists.
Accuracy vs. Precision
Accuracy and Precision
• Accuracy:
– the degree to which the result of a measurement,
calculation, or specification conforms to the
correct value or a standard.
• Precision:
– Related to reproducibility and repeatability
– Exactness
– Related to those other points / values around it
Scientific Method
• What is it?
– It is a process that is used to find answers to questions
about the world around us.
• Is there only one Scientific Method?
– No, there are several versions of the scientific
method. Some versions have more steps, while others
may have only a few. However, they all begin with the
identification of a problem or a question to be
answered based on observations of the world around
us and provide an organized method for conducting
and analyzing an experiment.
• What is a hypothesis?
– It is an educated guess based on observations and
your knowledge of the topic.
• What is data?
– It is information gathered during an experiment.
Steps
1. Identify the Problem
What do you want to know or explain?
2. Form a Hypothesis
What do you think will happen?
3. Create an Experiment
How will you test your hypothesis?
4. Perform the Experiment
Follow your procedure to test your hypothesis
5. Analyze the Data
Is your data reliable? Does it support your hypothesis?
Simpson’s Experiments
• Analyze the Simpson’s Experiments.
• Keep in mind both experimental design and
the scientific method. For each one, answer
the four questions AS WELL AS these three
prompts…
– What is the Problem?
– What is the Hypothesis?
– What is the Data?
If your data is inaccurate or flawed…
• Modify your experiment
– Rewrite your procedure to address the flaws in
the original experiment
If your data is NOT inaccurate or
flawed…
• Communicate the Results
– Write a conclusion that summarizes the important parts of
your experiment and results.
– Explain why you got the results that you did and what
those results mean.
Ethical Traditions of Science
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Value peer review
Truthful reporting of methods and outcomes
Making work public
Sharing a lens of professional skepticism when
reviewing the work of others
Warm up (9-2-14)
• Come in, grab a warm-up sheet from the front
table, find your seat and get started answering
your warm up..
• Design an experiment about the human
body’s response to exercise.
– Please be specific and detailed. Remember the
parts of experimental design in your answer!
Outline
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Objectives
Scientific Method Review
Peer Review
Experimental design Practice
Objectives
• Determine the importance of peer review and
practice using peer review to evaluate the
work of scientists.
• Practice experimental design and evaluating
experiments using the guidelines established
for good experimental design.
Scientific Method…
• What is it?
• Steps?
• Tell me what you know
Peer Review a Scientific Article
• Peer review methods are employed to
maintain standards of quality, improve
performance, and provide credibility.
• Often used to determine an academic paper's
suitability for publication.
• http://science.howstuffworks.com/innovation
/scientific-experiments/scientific-peerreview.htm
Media Sometimes Exaggerates Science
• http://www.cmaj.ca/content/170/9/1399.full.
pdf&embedded=true
• What does this article have to say about the
accuracy of reporting in the media?
Peer Review
• Is the evidence presented appropriate and sufficient
to support the claims??
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Physical Science
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http://www.sciencedaily.com/releases/2010/08/100802101813.htm
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Biology
http://www.thehindu.com/opinion/lead/lead-article-ebolas-reemergence-awakeup-call/article6357471.ece
Earth Systems
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http://leisureguy.wordpress.com/2007/09/04/the-scientific-consensus-on-global-warming/
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Biology II
http://www.sciencedaily.com/releases/2014/08/140828142752.htm
Warm up (9-3-14)
• Explain why experimental design is important
to an experiment.
• Describe how the scientific method,
experimental design, and peer review are all
connected.
Outline
• Objectives
• Peer Review Discussion
• Experimental Design packet
Objectives
• Practice using peer review to evaluate the
work of scientists.
• Practice experimental design and evaluating
experiments using the guidelines established
for good experimental design.
Discussion
Warm up (9-4-14)
• What does peer review have to do with
science?
• What is the significance of making sure that
everyone is using good experimental design
techniques?
• Do you need to use experimental design in
this class? Why?
Outline
• Objectives
• Experimental Design packet
• Experimental Design discussion
Objectives
• Practice experimental design and evaluating
experiments using the guidelines established
for good experimental design.
Graphing Experimental Data
• http://gbhsweb.glenbrook225.org/GBS/Scienc
e/chem/chem163/projects/factory/quiz.htm
• Graph the results from the table
• Be sure to label the axis and title your graph
(keep in mind independent and dependent
variables)
• Use appropriate scales
• How would I find the slope of this data?
What does the slope mean for science?
• It is the interaction between the independent and
the dependent variables
Proportionality
• two variables are proportional if a change in one
is always accompanied by a change in the other,
and if the changes are always related by use of a
constant.
• Directly proportional: y=cx
• Inversely proportional: y=c/x
• Inversely Proportional: when one
value decreases at the same rate that the
other increases.
• Directly proportional: as one amount
increases, another amount increases at the
same rate.
Warm-up (9-5-14)
• If you were planning on conducting an
experiment and you wanted to make sure that
you got funding… What are the steps you
should be sure to follow?
• What are the purposes of experimental
design?
Outline
• Objectives
• Experimental Design Quiz
• Ten Unanswered questions in science
Objectives
• To demonstrate knowledge of Experimental
Design and Peer Review
• To explore the top 10 questions about the
Earth and develop possible answers.
Earth Systems
• Ten Unanswered Questions
• http://www.livescience.com/4849-top-10questions-earth.html
Quiz!
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For this quiz…
No talking
You may use your notes, and only your notes
When you finish make sure that you are
working on something to keep yourselves
quiet.
• If you talk after you have turned in your quiz,
points may be taken off.