AS EDEXCEL statistics unit 1

Revision for statistics one, through the chapters in the text book

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CHAPTER 1

CHAPTER 1

  • Mathmaticals models simplify real life issues
  • Quick and easy to produce, improves understanding of the real world, enables predictions
  • Only give a partial description, only work for a certain range of values
  • Quantitative- describe data numerically
  • Qualitative- describe non numerically
  • Discrete- Can only be certain numbers/categories
  • Continuous-Can be of any Value
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CHAPTER 2

CHAPTER 2

  • Grouped data consists of classes and their class frequencies
  • +/- 0.5 onto class boundaries if there is a gap between the classes
  • modal class has highest frequency
  • median is middle value when the data is ordered, for discrete data work out by dividing n by 2.
  • For continuous grouped data use interpolation
  • INTERPOLATION: Find median value by dividing n by 2.
    • Work out the fraction that median value is through that class
    • times by the class width
    • Add on lower boundary  eg   25.5+ 0.5x(30.5-25.5)
    •                                                                12
  • MEAN: sum of x            OR       Sum of frequencies x mid point
  •                    n                                         sum of the frequencies
  • Use coding to simplify, then reverse any action taken to get the correct answer
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CHAPTER 3

CHAPTER 3

  • Lower quartile is the 25th percentile for discrete data divide n by 4. For continuous grouped, use INTERPOLATION
  • Upper quartile is the 75th percentile, for discrete data divide n by 4 then times by 3. For continuous grouped data use INTERPOLATION
  • IQ range = UQ-LQ
  • VARIANCE **see formula sheet
  • STANDARD DEVIATION: square root of variance, **see formula sheet

  • Coding for standard deviation and variance doesn't change anything.

  • Multiplying or dividing does, so when you get a value via coding, do the reverse operation to it.
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CHAPTER 4

CHAPTER 4

  • Stem and leaft diagram can be used to display data, must include a key. To compare two sets of data a back-to-back stem and leaf diagram can be used
  • A box plot represents important features of a set of data
    • quartiles
    • maximum and minimum
    • Outliers
  • If data is grouped continuous, then a histogram can be used to represent data. The height of the bar is frequency density, the area is frequency, and the width is the class width.
  • FREQUENCY DENSITY: worked out using a formula ** see formula sheet.
  • Skewness of data described using:
    • quartiles
    • shape of box plot
    • meaasures of location
    • FORMULA ** see formula sheet
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CHAPTER 5

CHAPTER 5

  • P(A U B) everything in the circles of the venn diagram, A, B or both
  • P(A n B) events A and B (intersection)
  • P(A') Everything that isnt event A
  • Complementary probability: P(A')= 1- P(A)
  • Addition rule: P(A U B) = (P(A) + P(B)) - P(A n B)
  • Conditional probability: P (A given that it is in B) = P(AlB) = P(A n B)
  •                                                                                                               P(B)
  • Multiplication Rule: P(A n B) = P(AlB) x P(B) OR P(BlA) x P(A)
  • Independant if: P(A n B) = P(A) x P(B)
  • Mutualy exclusive if: P(A n B) = 0
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Comments

Josh Kashdan


This chapter 5 information is very helpful thankyou

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