What about quarters

What about statistics, billing and quarters?

In general, that should also be pretty straightforward. If you have something that is billed on a monthly basis, just readjust the price and continue billing monthly. Of course, some businesses will try to sneak in a price increase, but that may also happen when a country changes currency, and legislation has to keep that in check.

If something is billed by the hour or per consumption/use, just do it as before: sum up the amount for all the days per month or quarter and bill that. There are already companies (also for flat rates) that bill, let’s say, every 30 days because it’s often simpler to keep the time-frame constant, and it makes numbers between invoices more comparable.

Monthly statistics should, in general, be even simpler and more stable. With the Gregorian Calendar, you have to either accept the fact that the lengths of the months are all over the place, or normalise for the month length. With SAC13, you can do the same - just ignore that there sometimes are months with a day more, or normalise for the length of the month too.

If you need to report quarters, you just sum up the respective weeks (for example, to get Q2, sum up weeks 14-26). If you don’t have weekly numbers, you can do a weighted sum of the relevant months. For example, for Q2, like so:

$$ \frac{3}{4}\cdot\text{June}+\text{July}+\text{August}+\frac{2}{4}\cdot\text{September} $$