importance of statistics in scientific...
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International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Importance of Statistics in Scientific Research
Christopher J. Malone, PhDWinona State University, Winona, MNEmail: [email protected]
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
Force
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
Force
Oops, backwards
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
ForceHigh School Project
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
ForceTheory
High School Project
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
Forcemass speed
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Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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Slush is most
dangerous
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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Slush is most
dangerousRight?
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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15904390 * 4380
2nd Trial
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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15904390 * 4380
2nd Trial
Yea, but
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExample 1
HollywoodVersion
436044104410*
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Measurement details should be in research plan › What are you going to measure?› How are you going to measure?
› Measurement issues go beyond identification of independent and dependent variables
› Outcomes must be measurablee.g. “I will identify the day the plant wilts” is not
precise; carefully measuring soil moisture over time is much better
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Numerical measurements are generally better than categorical measurements; however, avoid changing data types
Categorical Now, numerical
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Numerical measurements are generally better than categorical measurements; however, avoid changing data types
› Why? Averages, Standard Deviations, Correlations, etc.
Categorical Now, numerical
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Comparing Averages…
Averages0.670.50
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Comparing Averages…
Averages0.670.50
0.000.50
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Measurement issues/concerns are often overlooked› The necessity of precision in measurements cannot be
overstated
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Measurement issues/concerns are often overlooked› The necessity of precision in measurements cannot be
overstated
› _
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
› How good is my shot?
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
› How good is my shot?
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
› How good is my shot?
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
› Replication allows us to estimate the error due to variables that are not under our control (i.e. noise)
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
› Replication allows us to estimate the error due to variables that are not under our control (i.e. noise)
› Which in turn allows us to measure and possibly attribute an observed outcome to the variables that areunder our control (i.e. effect)
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
› Replication allows us to estimate the error due to variables that are not under our control (i.e. noise)
› Which in turn allows us to measure and possibly attribute an observed outcome to the variables that areunder our control (i.e. effect)
› _
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Usually inappropriate to display raw data, especially for high school projects
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Usually inappropriate to display raw data, especially for high school projects
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Usually inappropriate to display raw data, especially for high school projects
› Bar charts should only be used for tallys, not for numerical measurements (including averages)
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Bar charts should only be used for tally’s, not for numerical measurements (including averages)
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Usually inappropriate to display raw data, especially for high school projects
› Bar charts should only be used for tally’s, not for numerical measurements (including averages)
› Bring back the dot plots! › Simple to construct and easy to read› Stack them to compare groups
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Bring back the dot plots!
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Bring back the dot plots!
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Bring back the dot plots!
Adding Averages, v 1 Adding Averages, v 2
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Generally speaking…› Excel is less than optimal for constructing displays› Numerical data require numerical data displays
› Compute change for paired measurements
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Generally speaking…› Excel is less than optimal for constructing displays› Numerical data require displays for numerical data
› Compute change for paired measurements
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Generally speaking…› Excel is less than optimal for constructing displays› Numerical data require displays for numerical data
› Compute change for paired measurements› % change may be necessary at times
› Scatter plots tend to be under utilized
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› Generally speaking…› Excel is less than optimal for constructing displays› Numerical data require displays for numerical data
› Compute change for paired measurements› % change may be necessary at times
› Scatter plots tend to be under utilized
Your summaries and displays should support your story.
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› _
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International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
The Statistical Chapter of your Story
Thoughts
› These elements will give statistics an opportunity to help tell your story› Good experimental design techniques› The collection of precise and error free
measurements› The use of appropriate statistical methods› Interpretations that are meaningful and given within
context
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
The Statistical Chapter of your Story
Thoughts
› Borrow ideas and concepts from others › e. g. Marketing› e. g. What are the important elements of an
effective persuasive speech? -Learn from Jack Franchetti @ 10:00AM tomorrow…
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
The Statistical Chapter of your Story
Thoughts
› Borrow ideas and concepts from others › e. g. Marketing› e. g. What are the important elements of an
effective persuasive speech? -Learn from Jack Franchetti @ 10:00AM tomorrow…
› In the end, your story may be different than your original hypothesis.
› Many of the young scientists here are not presenting their original hypothesis.
› This is indeed the essence of the scientific method!
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
› Compliments of Wendy Greenberg, Biology Department, Bemidji State University
› Set-up: 1. Play game 5 times with sound,
then 5 times without sound2. Measurement: Score3. Issues???
Examples
Example #1 (Video Games and Sound)
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & A
› Compliments of Wendy Greenberg, Biology Department Bemidji State University
› Set-up: 1. Play game 5 times with sound,
then 5 times without sound2. Measurement: Score3. Issues???
Note: Student recognized issue of potential improvement due to learning, but his solution was to switch the order!
Examples
Example #1 (Video Games and Sound)
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› My hypothesis: Does colored water change the color of a
flower?
› Set-up: 1. What should I measure?2. The type of flower is irrelevant to me, but I will use a
rose and tulip for my experiment. 3. Do I need a control? Why or why not?4. I have room for 16 planting pots in my lab.
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› Sketching an appropriate randomization plan
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› The Data
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› The averages
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
International Science and Engineering FairMay 10, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Thank you!
Chris MaloneWinona State University
Email: [email protected]