Normal

• Normal distribution - used for continuous data, denoted by N(µ,var)
• Normal conditions

  Bell curve

  Equal Averages

  Random events

  Independent events

  Empirical law

  Symmetric
• Empirical law 


  • μ ± σ = 66.6% of data
  • μ ± 2σ = 95% of data
  • μ ± 3σ = 99.8% of data
• How do we find exact probabilities?


  N/A as always = 0
• How do we find cumulative probabilities


  Normal CD
• How do we find a value for x?

  Inverse normal
• Exam technique for normal

  • if given a sample and asked to explain why it is a suitable model / not you must compare sample data to the empirical law
  • to calculate μ and / or σ use the formula Z = X - μ / σ
  • if you require a Z value, use the standard normal N(0,1)