Stats

Question 1

Mean of a DRV?

Answer 1

Multiply x and p and add each value

Question 2

What is DRV?

Answer 2

-Can only take discrete values and probability adds to 1

Question 3

What is the expectation of a DRV?

Answer 3

• the mean , sum of xp

Question 4

How to work out E(Y)

Answer 4

y = ax +c
E (y) = E( ax +c)
E (y) = a x E(x) +c

Question 5

Variance of X in a DRV?

Answer 5

Var (x)= E (x^2) - E(x)^2

Question 6

Standard Deviation (σ)? equation

Answer 6

square root of variance

Question 7

Variance rules?

Answer 7

Var (a) = 0
Var (ax) = a^2 var (x)
Var (ax +b) = a^2 var x

Question 8

How to work out variance when you multiply them out?

Answer 8

Var(xy) -E(x^2) E(y^2) - (E(x) E(y)) ^2

Question 9

Mean of CRV?

Answer 9

X x f(x) dx

Question 10

Variance of CRV?

Answer 10

x^2 x f(x) - (E(x))^2

Question 11

Median?

Answer 11

-Integrate f(x)
-(M) as median
-lower bound as one in question
- equals to 0.5

Question 12

Lower Quartile

Answer 12

-Integrate f(x)
-(Q) as lower quartile (upper bound)
-lower bound as one in question
- equals to 1/4

Question 13

Upper Quartile

Answer 13

-Integrate f(x)
-(Q) as upper quartile (upper bound)
-lower bound as one in question
- equals to 0.75

Question 14

To work out a percentile?

Answer 14

-Integrate f(x)
-(y) will be your answer (upper bound)
-lower bound as one in question
-equals to percentile as a decimal

Question 15

What is PMCC used for?

Answer 15

linear relationships

Question 16

How do outliers affect pmcc?

Answer 16

effect the correlation coefficient

Question 17

When is PMCC valid?

Answer 17

-data from bivariate normal distrubution