Date post: | 26-May-2015 |
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Defusing StatisticsTracey Minzenmayer
SCC/MLA 2007
The BasicsStatistics is about• describing data• drawing conclusions based on the data
Discrete & Continuous Variables
A variable is something that CHANGES
6 lb < 8 lb < 10 lb
Assessment: Discrete &
Continuous Variables• Dog Breed: discrete or
continuous?Discrete
• Length of Cat Whiskers: discrete or continuous?
Continuous
Independent & Dependent Variables
Independent Variables• Class size• Example or exercise• Length of class• Catnip or milk
Independent & Dependent Variables
Dependent Variables• Grade on final assignment• Choosing correct search terms• Confidence level
The Normal Curve
Over half the values are within one standard deviation of the mean
Outlier- a value far away from the rest of the values
Standard Deviation
• A measure of how closely together your values are clustered
Different Standard Deviations
Assessment: Variables & Standard Deviation
• Search example: Discrete or continuous? Independent or dependent?
• Score on assignment: Discrete or continuous? Independent or dependent?
Statistical Analysis
• Null hypothesis: I won’t find anything
• Alternative hypothesis: There’s something in there!
A Word About Trends. . .
Photo Credits• http://commons.wikimedia.org
– Tim Bartel (slide 6)– Julian Cantarelli (slide 13)
• http://www.morguefile.com– Tim Hansen (slide 9)– Michelle Kwajafa (slide 15)– Mary A. Pen (slide 8)– Gracey Stinson (slide 2)– Luis C. Tejo (slide 3, cat)– Dawn M. Turner (slides 8, 12)– Mary R. Vogt (slide 14, both dogs)– Stuart Whitmore (slide 3, cat on pumpkin)
• http://www.flickr.com– Ryan Forsythe (slide 5)