Measures of dispersion

• What are the measures used for dispersion

  Range.

  Interquartile range.

  Variance.

  Standard deviation.
• What is the downside of using range

  It is affected by outliers
• What measures the spread about the mean

  Variance and standard deviation
• How are outliers calculated above Q3


  (1.5 * IQR) + Q3
• How are outlisers made below Q1

  Q1 - (1.5 * IQR)
• What is sigma squared

  Population variance
• What is S squared

  Sample variance
• What is Sigma

  Population standard deviation
• What is S

  Sample standard deviation
• What is equation is this

  Population variance

  
• Equation for sigma squared

  The sum of x - sample mean squared all divided by N.
• Equation for S squared

  The sum of X - X bar squared is divided by n - 1.
• What equation is this

  Sample variance

  
• What is sigma

  Population standard deviation
• What is S

  Sample standard deviation
• What proportion of data is within 1 standard deviation on a normal graph

  68
• What proportion of data is whithin 2 standard deviaitons on a normal graph

  95
• What proportion of data is within 3 standard deviations on a normal graph

  99.7