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Stats Exam #2
Chapter 4-5
Question | Answer |
---|---|
definition of experiment | Process by which a measurement is taken or observations are made |
Examples of experiment | Flipping a coin or rolling a die |
definition of outcome | the result of an experiment |
examples of outcomes | Heads or rolling a 3 |
definition of sample space | the listing of all possible outcomes |
Example of sample space flipping a coin | S={H,T} |
Definition of event | an outcome or a combo of outcomes |
Example of event | even number of rolling a die |
Property 1 | "A probability is always a numerical value between 0 and 1" |
Property 2 | "The sum of probabilities for all outcomes of an experiment is equal to exactly 1" |
Empirical approach to probability | experimental |
Theoretical approach to probability | Classical (dont actually do the experiment) |
Subjective approach to probability | Expression of confidence (wheatherman) |
Empirical probability of A= | number of times A occured/ number of trials |
Law of Large Numbers | The more an even occurs the more the theoretical probablility is true |
Theoretical probability of A= | number of times A occurs in sample space/ number of the elements in the sample space |
odds in favor of event A | a to b or a:b |
odds against event A | b to a or b:a |
Proability of event A= | a/a+b |
Probability of event A will not occur= | b/a+b |
definition of conditional probability | Probability of an event GIVEN another event has occured |
definition of complimentary evnet | The compliment of A, Abar is the set of all sample points in the sample space that does not belong to event A |
Example of complimentary events | If A is heads the Abar is tails |
Formula for complimentary events | probability of A compliment= one- probability of A |
general addition rule: P(A or B)= | P(A)+ P(B)+ P(A and B) |
general multiplication rule: P(A and B)= | P(A) x P(B given A) |
definition of mutually exclusive events | Event that share no common elements |
Example of mutually exclusive events | heads or tails, red or black cards, number 2 and 5 |
P(A and B) in a mutually exclusive event | 0 |
Definition of an independent event | The occurrence or nonoccurrence of one gives us no information about the likliness of occurrence for the other. |
Formula for an independent event | P(A)= P(A given B)= P(A not given B) |
definition of dependent events | Occurrence of 1 event does have an effect on the probability of occurrence of the other event |
Special Multiplication rule | In 2 independent events P(A and B)=P(A) x P(B) |
definition of random variables | A variable that assumes a unique numerical value for each of he outcomes in the sample space of a probability experiment |
example of random variable | x={0,1,2} |
definition of discrete random variable | A quantitative random variable that can assume a countable number of values. |
definition of continuous random variable | A quantitative random variable that can assume an uncountable number of values. |
example of discrete random variable | number of heads when we flip a coin 10 times |
example of continuous random variable | distance from earth center to sun center. |
definition of probability distribution | A set of probabilities associated with each of the values of a random variable. it is a theoretical distribution used to represent populations |
ways to determine if there is a probability distribution | 1) each probability is between 0 and 1 2) the sum of the probabilities is 1 |
definition of probability function | A rule P(x) that assigns probabilities to the values of the random variable x |
sigma squared | variance |
sigma | standard deviation |
MU | mean |
definition of binomial experiment | an experiment with only 2 outcomes (success of failure). the trials are independent. p= success. |
MU in a binomial distribution | np |
variance in a binomial distribution | np(1-p) |