Expected Value Flashcards
1
Q
How to calculate expected value
A
e(x) = sum of all (x.p(x))
2
Q
if x and y are random variables
z = x + y
then what is E(Z)
A
E(Z) = E(X) + E(Y)
3
Q
what does variance measure
A
concentration around the expected value
4
Q
if g(x) = ax + b
a and b are constants
what is E(g(x))
A
aE(x) + b
5
Q
how is variance calculated
A
Var (x) = E |( x - miu)^2|
6
Q
how is standard deviation calculated
A
sqroot(variance)
7
Q
if x-miu is very small, then squaring it will make it
A
even smaller
8
Q
if x-miu is very large, then squaring it will make it
A
even larger
9
Q
how does variance work
A
penalises values that are further from the central tendency
10
Q
if x and y are independent variables what is
E(XY)
A
E(X)E(Y)
11
Q
if x and y are independent variables, what is
var (x+y)
A
Var(x) + var(y)
