statistics- chapter 5

sample space

S; sample space of a probability experiment is the collection of all possible outcomes

event

E; any collection of outcomes from a probability experiment; an event consists of one outcome or more than one outcome

Simple events

events with one outcome, e(i)

certain event

probability of 1

impossible event

probability of 0

unusual event

probability of 0.05 or less

approximating probabilities using the empirical approach

relative frequency of E = frequency of E/number of trials of experiment

computing probabilities

subjective probabilities

probability obtained on the basis of personal judgement

disjoint

also called mutually exclusive; have no outcomes in common; if they are disjoint the probability of 1 or 2 is the addition of those two probabilities.

contingency table

or two-way table because it relates two categories of data

independent events

two events are independent if the occurrence of event 1 does not affect the probability of event 2.

dependent events

the occurrence of event one affects the probability of event two happening

disjoint events

they have no outcomes in common (means they are not independent)

conditional probability

e.g. obesity rate for men and age (different rates for different age groups)
P (F/E0

conditional probability rules

P (F/E) = P(E and F)/PE