# summarising data

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• Created by: eleanor
• Created on: 11-04-15 12:48
• 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