summarising data

  • Created by: eleanor
  • Created on: 11-04-15 12:48
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  • Summarising Data
    • Linear Interpolation
      • Finding the median
        • Formula:
      • extend groups to show they are continuous
      • Find cumulative frequency
    • Mean and Standard Deviation
      • Mean
        • Is influenced by extreame values
        • used for symmetrical data or grouped data
        • Grouped Data
          • sum of (frequency x midpoint) / over total frequency
        • For a list
      • Standard Deviation
        • is a measure of dispersion or spread from the mean
        • Formula:
          • square the data then add them all up
          • The mean of x squared
        • grouped data:
          • square the x values then multiply by the frequencies then add them up
        • You then need to square root the answer to find the standard deviation
    • Coding
      • you mght be told that the dat is coded this is to make the numbers easier to work with
      • to find the mean of the original data quate the coded mean to the coding formaula and solve
      • to find the standard deviation of the original data ignore the addition and subtractions and equate


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