## Lost in translation (reprise)

Late last year I drew up a table of actuarial terms and their translation for statisticians.  I had thought that it was a uniquely actuarial trait to use different names compared to other disciplines.  It turns out that statisticians are almost as guilty.  Table 1 shows some common statistical terms in mortality modelling and their description for non-statisticians.

Table 1. Some statistical terms and their definition for mathematicians and engineers.

Statistical term Notation
Description
hazard function
variesThe instantaneous failure rate.
observed information matrixThe curvature of the log-likelihood function, i.e. the negative of the matrix of second partial derivatives.  This is the same as the negative of the Hessian matrix.
score function
The gradient of the log-likelihood function, i.e. its first partial derivative.

Our non-statistical readers will recognise the origin of the name of this blog.  If we had called it the Hessian, then things would have been very confusing indeed.