释义 |
Gaussian Distribution Linear Combination of VariatesIf is Normally Distributed with Mean and Variance , thena linear function of ,
 | (1) |
is also Normally Distributed. The new distribution has Mean andVariance , as can be derived using the Moment-Generating Function
which is of the standard form with
 | (3) |
 | (4) |
For a weighted sum of independent variables
 | (5) |
the expectation is given by
Setting this equal to
 | (7) |
gives
Therefore, the Mean and Variance of the weighted sums of Random Variablesare their weighted sums.
If are Independent and Normally Distributed with Mean 0 and Variance , define
 | (10) |
where obeys the Orthogonality Condition
 | (11) |
with the Kronecker Delta. Then are also independent and normally distributed with Mean 0and Variance . |