Ch6: Statistical distributions

• random variable definition


  a variable whose value depends on the outcome of a random event
• a variable is discrete when…


  it can only take certain numerical values
• a variable is random if…


  the outcome isn’t known until the experiment is carried out
• a probability distribution fully describes the probability of any outcome in a sample space 


  e.g. P(X=x) =1/6 x=1,2,3,4,5,6
• how do you define a binomial distribution?

  x~B(n,p)

  where:

  n is the fixed number of trials

  x is the number of successful trials

  p is the probability of a success

  the trials are independent

  there are 2 outcomes (success or fail)
• How can you show a probability distribution?

  A probability mass function (p(X=x)=1/6, x=1,2,3,4,5,6)

  a table with x on top and p(X=x) on bottom

  Using a diagram
• what is a discrete uniform distribution?

  when all the probabilities are the same
• The sun of all probabilities of all outcomes of an agent sum to?

  1
• When can you use the binomial cd on a calculator?

  when P(X<or equal to x)