Large sample

• What do we do if the population is not normally distributed?

  Use Central Limit Theorem

  • when the population distribution is unknown
  • and the sample is large (n>30)
  • the sample means are normally distributed
• What do we do if the population variance / standard deviation is unknown?


  Unbiased estimates:

  • when the population variance / standard deviation is unknown
  • and the sample is large (n>30)
  • the sample standard deviation / variance is an unbiased estimate