Probability

Question 1

What is the ‘frequentist approach’?

Answer 1

Relative frequency (‘frequentist’) approximation: proportion of times the outcome would occur in a long series of repetitions

p(x) = # times X occured / # times procedure was repeated

Question 2

Define sample space

Answer 2

Sample space: collection of all possible outcomes for an experiment

Question 3

Define event

• Simple events
• Compound events

Answer 3

• Event: a group of outcomes that share a feature of interest; a subset of the sample space
  
  • Simple events: happen only one way
  • Compound events: happen in more than one way (contain more than one outcome)

Question 4

Define independent and mutually exclusive events

Answer 4

• Independent: events A and B are said to be independent if knowing that one occurs does not change the probability that the other occurs
  
  • A dependent event is affected by the outcome of a second event
• Mutually exclusive: events have no shared outcomes

Question 5

Define conditional probability

Answer 5

• Conditional: the probability of event B knowing that event A has occured

Question 6

Define complement

Answer 6

• Complement of an event: all outcomes that are NOT the event