Basic Descriptive Statistics

Basic Descriptive Statistics

• 1.
  Basic Descriptive Statistics Mr. Siko Clarkston HS
• 2.
  Why?  Descriptive statisticsdo just that: Describe Data!  What we’ll cover in this slidecast – Mean (average) – Median – Mode – Range
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  Mean  Fancy Formula  What this means: add µ = ΣX/N up all your data, then divide by the number of data points
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  Mean Sample data: How to calculate: 98cm 76cm 98+76+82+54+90 = 82cm 400cm 54cm 90cm 400cm/5 = 80cm
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  Median  The medianis the middle data point in a set  To determine the median, sort the data from smallest to largest and find the middle data point
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  Median Sample data: Rearranged Data: 98cm 54cm 76cm 76cm 82cm 82cm 54cm 90cm 90cm 98cm
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  Median  If thereis an even number of data, there will be two middle points.  To find the median, take the average of those two data.
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  Median Sample Data: Rearranged Data: 4ml 2ml 8ml 4ml 12ml 8ml 2ml 12ml 4 + 8 = 12ml 12/2 = 6ml
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  Mode  The modeis the most frequently occurring data point.  To find the mode, arrange the data from smallest to largest, and then determine which amount occurs most often.
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  Mode Sample Data: Rearranged Data: 20g 23g 20g 20g 20g 30g 30g 22g 22g 27g 23g 23g 23g 23g 25g 20g 24g 23g 24g 25g 25g 23g 25g 27g 20g 23g 30g 30g
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  Range  The rangeis the distance between the smallest and largest data point.  To calculate, determine the smallest data point and the largest data point, then subtract the smallest from the largest.
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  Range Sample data: Rearranged Data: 98cm 54cm 76cm 76cm 82cm 82cm 54cm 90cm 90cm 98cm 98cm – 54cm = 44cm
• 13.
  Recap  Mean, Median, Mode, and Range “describe” the data.
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  Acknowledgements American Chemical Society.(2006). Chemistry in the community: ChemCom (5th ed). New York: W.H. Freeman