Methodology
This page explains how work on the material is organised: where topics come from, what the conclusions rest on and where the limits of what is written lie.
How topics and data are chosen
We take on questions that keep coming back and work through them on data with the source and the period stated.
Limits of applicability
The texts explain how things generally work but do not account for particular circumstances. A decision with consequences needs a consultation with a qualified specialist.
Reviewing what is published
We come back to a text when the figures or rules it describes go out of date. Cosmetic edits do not count as an update.
Material on this site is prepared and checked by Sarah Whitfield.