The standard deviation is calculated as the square root of the diagonal of
the variance coavariance matrix of your random parameters. The variance-
covariance matrix is calculated using the estimated lower Cholesky matrix.

## Arguments

- a
An integer indicating the row position of the random parameter in the
asymptotic variance-covariance matrix

- L
The lower cholesky matrix

- lambda
The asymptotic variance covariance matrix

## Value

A vector of standard errors

## References

http://www.stephanehess.me.uk/software.html
Daly, A. J., Hess, S., & de Jong, G., 2012, Calculating errors for measures derived
from choice modelling estimates, Transportation Research Part B, 46(2):333-341