5.1 Flashcards
What is a random variable
- a numerical description of the outcome of n experiment
- must always assume numerical values
What is a discrete Random variable
- exact or finite
- ex# of books, age
- can count them
- # of customers
- values of f(x) must be great than or equal to 0
with a discrete random variable what must the values be
the value of f(x) must be great than or equal to 0
What is a continuous random variable
- infinite
- glass of water
- infinitely divisible
- collection of intervals
- experimental outcomes based on measurements of scale such as
- temperature, size, weight, distance and time
The probability distribution describes what for a random variable
describes HOW prob(s) are distributed over the values of the random variable
What is the prob distribution for a discrete random variable x
- a prob function
- denoted by f(x)
- provides the prob for each value of the random variable
What are the methods for prob distribution of a discrete random variable x
- relative frequency method
- Classical Method
- Subjective method
When would you use the relative frequency method in a prob distribution of a discrete random variable x
use when reasonably large amounts of data are available
- treat the data as though it was a POPulation
- more widely used in practice
- when used for discrete prob dist. leads to what is called an empirical discrete distribution
when would you use the classical method for a prob distribution of a discrete random variable x
- use when experimental outcomes generate values of the random variable that are equally likely
When would you use the Subjective Method for a prob distribution of a discrete random variable x
- individual uses their best judgement to assign each prob
- can also lead to a table of values of the random variable together with the associated prob(s)
What are the required conditions for a discrete Prob Function
f(x) >= 0 Sum f(x) = 1
- meet all above, is a valid discrete prob function
