Probability 2 Flashcards
Probability, random variables
Random process
We know what outcomes could happen but don’t know which one will happen
probability 0 >=P<=1
Frequentist interpretation
Bayesian interpretation
Frequentist: probability measures the frequency of various outcomes of a random process an infinite number of times.
Bayesian: each value has its own probability of becoming true
Law of large numbers
more observations cause the proportion of the outcome to = the probability
gambler’s fallacy/law of averages
think they are due for a win because of Law of large numbers
Disjointed outcomes
Cannot happen at the same time
Non-Disjointed outcomes
Can happen at the same time
set element subset complement union intersection empty set Disjoint Difference
set-the large area S element-a value in a set subset-set A is fully in S complement= S-A union=A+B intersection=A,B overlap empty set=no elements Disjoint= intersection between non-overlapping sets Difference= A-B elements in a that are not in B
Probability Distribution and rules (3)
A table stating the probability of outcomes.
- ) events must be disjointed.
- ) probabilities are between 0 and 1
- ) total up to 1
Experiment, Sample space, Event, Probability function, Discrete sample space
Experiment- repeatable procedure with well defined possible outcomes
Sample space-the set of all possible outcomes
Event- a subset of the sample space/collection of outcomes
Probability function- a function giving probability to each outcome
Discrete sample space- a list-able sample space finite or infinite
The probability function
P assigns w a probability P(w).
- has to be within 0-1
- sum of all possible outcomes =1
Rules of Probability 3
P(S-A)=1-P(A)
- if A and B are -disjointed P(A or B)= P(A)+P(B)
- non disjointed p(A or B)= P(A)+P(B)-P(A and B)
Process independence
Independent if knowing the outcome of one does not give info about the other
Marginal Probability
Chance of one event Occurring
Joint Probability
Chance of two events Occurring
Conditional Probability
Chance of outcome Occurring if one outcome is already known P(A|B)=P(A+B)/B
multiplication of dependent variables
P(A and B)=P(A|B)*P(B)
Independence Math
If A is independent
P(A|B)=P(A)
Law of total probability
subset A is equally apart of 3 equal subsets B1-3
P(A)=P(A and B1)…
P(A)=P(A|B1)P(B1)..
Bayes theorem
I cant