importance of statistics in scientific research final...
TRANSCRIPT
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Importance of Statistics in Scientific Research
Christopher J. MaloneEmail: [email protected]
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
Force
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
Force
Oops, backwards
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
ForceHigh School Project
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Hypothesis
ForceTheory
High School Project
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
Forcemass speed
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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Slush is most
dangerous
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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Slush is most
dangerousRight?
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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15904390 * 4380
2nd Trial
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
The Experiment
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15904390 * 4380
2nd Trial
Yea, but
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExample 1
HollywoodVersion
436044104410*
MN State Science and Engineering FairMarch 27, 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
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Numerical measurements are generally better than categorical measurements; however, avoid changing data types
CategoricalNow, numerical
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Numerical measurements are generally better than categorical measurements; however, avoid changing data types
CategoricalNow, numerical
› Why? Averages, Standard Deviations, Correlations, etc.
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Average = 3.5
› Correlation = 0.392
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Measurement issues/concerns are often overlooked› The necessity of precision in measurements cannot be
overstated
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Measurements
Thoughts
› Measurement issues/concerns are often overlooked› The necessity of precision in measurements cannot be
overstated
› _
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
Replication Precision
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
Replication Precision
› Replication allows us to estimate the ‘error’ due to variables that are not under our control (i.e. noise)
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
Replication 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)
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Replication
Thoughts
› Generally speaking, more is better› May be necessary to balance replication and precision
Replication 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 possibility attribute an observed outcome to the variables that areunder our control (i.e. effect)
› _
MN State Science and Engineering FairMarch 27, 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
MN State Science and Engineering FairMarch 27, 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 are under utilized
› Your summaries and displays should support your story
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Summaries and Displays
Thoughts
› _
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MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
The Statistical Chapter of your Story
Thoughts
› The following elements will give statistics an opportunityto help tell your story› Good experimental design techniques› The collection of precise and error free
measurements› The use of appropriate statistical methods› Give interpretations meaning and ensure outcomes
are discussed within context
MN State Science and Engineering FairMarch 27, 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? › In the end, your story may be different that your
hypothesis. This is OK and is indeed the essence of the scientific method!
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
The Statistical Chapter of your Story
Thoughts
› Borrow ideas and concepts from others › Marketing› What are the important elements of an effective
persuasive speech? › In the end, your story may be different that your
hypothesis. This is the true essence of the scientific method!
› _
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
The Statistical Chapter of your Story
Thoughts
› Borrow ideas and concepts from others › Marketing› What are the important elements of an effective
persuasive speech? › In the end, your story may be different that your
hypothesis. This is the true essence of the scientific method!
› _
› Final score for ?
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Final thought
Thoughts
› The method of science is more stable, and more important to men [and women] of science, than any particular result achieved by its means.
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & A
Final thought
Thoughts
› “The method of science is more stable, and more important to men [and women] of science, than any particular result achieved by its means.” (Cohen, 1934)
MN State Science and Engineering FairMarch 27, 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)
MN State Science and Engineering FairMarch 27, 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)
MN State Science and Engineering FairMarch 27, 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.
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› Sketching an appropriate randomization plan
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› The Data
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AExamples
Example #2 (Influencing the color of a flower)› The averages
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Bar chart onnumerical data
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Statistical inference &
error bars for averages
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Calculations &
Raw Data
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Replication needed on Control
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Bar chart onaverages; Includes
Standard error bars
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Bar graphs for
paired data and
averages
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Needs Scatter plot instead of
bar graph withtrend line
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Scatter plotsand
trend lines
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
< The Good
The Bad >
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Correlations with statistical tests
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Q & A Session
Table with data and picture of
location of failures
MN State Science and Engineering FairMarch 27, 2010
Thoughts ExamplesExample 1 Q & AQ & A
Thank you!
Chris MaloneWinona State University
Email: [email protected]