M2. Variance

Question 1

Define variance

Answer 1

The variability/spread of the distribution given by the mean of the difference between the variable and its expectation.

By defintion, must be non-negative.

Question 2

Equations for variance

Answer 2

Question 3

Standard deviation and variance

Answer 3

Standard deviation is the square root of the variance.

Question 4

Formula for the variance for a uniform distribution

Answer 4

Question 5

Formula for variance of binary/indicator variables

Answer 5