EC285 Chapter Notes - Chapter 7: Randomness, Sample Space
Document Summary
With random phenomena, we can"t predict the individual outcomes, but we can hope to understand characteristics of their long-run behavior. For any random phenomenon, each attempt, or trial, generates an outcome. The term event refers to outcomes or combinations of outcomes. Sample space is a special event referring to the collection of all possible outcomes. The probability of an event is its long-run relative frequency (35/100 = 0. 35) Independence means that the outcome of one trial doesn"t influence or change the outcome of another. Theoretical probability: (cid:4666)(cid:1827)(cid:4667)=# (cid:1867)(cid:1858) (cid:1867)(cid:1873)(cid:1872)(cid:1855)(cid:1867)(cid:1865)(cid:1857)(cid:1871) (cid:1866) (cid:1827) (cid:1872)(cid:1867)(cid:1872)(cid:1853)(cid:1864) # (cid:1867)(cid:1858) (cid:1867)(cid:1873)(cid:1872)(cid:1855)(cid:1867)(cid:1865)(cid:1857)(cid:1871) Rule 1 a probability is a number between 0 and 1. Rule 2 probability assignment rule: the probability of the set of all possible outcomes must be 1 (cid:4666)(cid:4667)=(cid:883) (cid:4666)(cid:1827)(cid:4667)=(cid:883) (cid:4666)(cid:1827)(cid:4667) S represents the set of all possible outcomes and is called the sample space. Rule 3 complement rule: the probability of an event occurring is 1 minus the probability that it doesn"t occur.
