### Trueness

The trueness of an analytical method, which describes the consistency between
an analytical result and a reference value, can be tested in different ways.
Possible procedures are analysis of a reference material, comparison to a 
(different) reference method or analysis of samples of specified concentration(s).

For the latter, $n \le 6$ independent samples should be prepared and analyzed at 
3 different concentration levels $j$ covering the working range. For each level,
the recovery should be calculated by comparison with the reference value as
$$R = \frac{\overline{x_j}}{x_{r,j}} \times 100\%$$
where $\overline{x_j}$ is the mean value of all replicates at level $j$ and 
$x_{r,j}$ is the according reference value. Recovery values $80\% \le R \le 120\%$
are acceptable.

Currently, *eCerto* only allows to copy/paste a statement regarding the recovery 
calculations which will be stored together with the other data and incorporated
in the report.