Utente:Ancelli/traduzioni-calcolatrici

NOMOGRAMMA

Food risk assessment nomogram

[[:File:Risk Based Sampling Nomogram (3yr).png|right|200px|thumb|Food risk assessment nomogram.]] Although nomograms represent mathematical relationships, not all are mathematically derived. The following one was developed from the graphical end to achieve appropriate end results that could readily be defined by the product of their relationships in subjective units rather than numerically. The use of non-parallel axes enabled the non-linear relationships to be incorporated in the model.

The numbers in square boxes denote the axes requiring input after appropriate assessment.

The pair of nomograms at the top of the image determine the probability of occurrence, and the availability, which are then incorporated in the bottom multistage nomogram.

Lines 8 and 10 are ‘tie lines’ for the transition between the stages of the nomogram.

The final pair of parallel logarithmic scales (12) are not nomograms as such, but reading-off scales to translate the risk score (11, remote to extremely high) into a sampling frequency to address safety aspects and other ‘consumer protection’ aspects respectively. This stage requires political ‘buy in’ balancing cost against risk. The example uses a 3 year minimum frequency for each, though with the high risk end of the scales different for the two aspects, giving different frequencies for the two, but both subject to an overall minimum sampling of every food for all aspects at least once every three years.

This risk assessment nomogram was developed by the UK Public Analyst Service with funding from the UK Food Standards Agency for use as a tool to guide the appropriate frequency of sampling & analysis of food for official food control purposes, intended to be used to assess all potential problems with all foods, although not yet adopted.