# The Railways and Other Guided Transport Systems (Safety) Regulations 2006, Paragraph 13: Moving weighted averaging process for the annual assessment of achievement of NRVs


For each of the risk categories to which the MWA is applied for carrying out, in each year Y (starting from Y = 2010), the assessment steps described in paragraphs 9 to 12, the following phases must be applied for calculating the MWAY
(a) calculation of the annual observations OBSi returned by the corresponding indicators in paragraph 14 after providing as input the relevant data for the relevant years (the index i takes the values as defined in the formula in sub paragraph (e));
(b) calculation of the 5-year average (AV) of annual observation OBSi;
(c) calculation of the absolute value of the difference ABSDIFFi between each annual observation OBSi and the AV. If ABSDIFFi < 0.01 * AV, the ABSDIFFi is attributed a constant value equal to 0.01 * AV;
(d) calculation of the weight Wi by taking the inverse of ABSDIFFi;
(e) calculation of the MWAY as follows—
M W A Y Y = ∑ i = x N W i × O B S i ∑ i = x N W iwhere i is a natural number and x = Y – 6; N = Y – 2.

---
Source: https://www.legislation.gov.uk/uksi/2006/599/schedule/11/paragraph/13 (the official version)
Page: https://openlegislation.uk/railways-and-other-guided-transport-systems-safety-regulations-2006/schedule-11/paragraph-13
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.