Random Variables: Discrete vs Continuous
Discrete Random
Variable
Domain
Isolated values on
the number line.
Description of Chart of outcomes
Probability
and associated
Distribution
probabilities.
(which values can
x
7
8
9
be taken on and
P(x) .3
.5 .2
how to assign
probability to
them)
Plot
Probability
or name:
 binom(10,.3)
Probability
Histogram
Continuous Random
Variable
All values in an interval
of numbers.
Name (if possible)




N(100,10)
~N(300,20)
X2(6)
t(200,20)
Probability Density
Curve
Adding up discrete Area under curve for
probabilities of
the range of interest
interest.
P(X≤8) = .3+.5
Mean
Standard
Deviation
Law of Large
Numbers
Balance point of
histogram
Cannot be
observed in plot
Holds
Balance point of
density curve
Only can observed if
plot is normal
Holds