Evidence3 of 6
How we keep it right
A comparison is right only while its prices and its rules are. This is what is done to keep them so, and what happens when something changes.
- Prices read from what each provider publishes
- A sharp move, or a changed page, waits for a person
- Every rule dated to its last check
When prices are read
What happens to a provider’s prices when they are read again and something has moved.
Read
From what the provider publishes, on a schedule, for each region it prices: its price list, or its own pricing pages where it has none.
Dated
Kept with when it was read, and with the provider’s own version or publication date where it gives 1.
Compared
Against the prices in use. From a price list, a refresh in which nothing moves by more than a set amount is put in use.
Held, if it moves sharply or was read from a page
A price that moves by more than that amount waits for a person, and so does every change read from a provider’s pricing pages. Comparisons go on using the prices before it.
A rate is read, not typed
Rates come from the provider’s price list, or, where it publishes none, from the figures on its own pricing pages, each kept with the page it was read from. A fee a provider publishes only on a page of its documentation is held as a rule, with that page.
A result states both dates
When its prices were read, and the date the provider gives them, where it gives 1.
Said to be old when they are
A result whose prices are older than a set age says so, on the screen and in the PDF.
The rules behind a charge
A price list gives rates. How a charge is worked out, such as a minimum storage duration, is on the provider’s documentation, and each rule is held with the page it came from.
Every cited page is read again regularly
A page that has moved or gone is flagged.
A changed page is checked against its rule
A rule is confirmed only on words found on the page itself.
A change is proposed, never applied by itself
Where a provider’s page states a different value, the change is put to a person with the words that were found. Nothing changes a rule until a person applies it.
Every set of rules carries a date
The date it was last checked against its sources, which every result priced with it states.
The calculation
Every option shows its working
Each charge behind a total is listed as how much of it there was, the rate paid for it, and what it came to, and the charges are added up to the total in front of you.
Tested against real price lists
The calculation is run in automated tests against captured copies of each provider’s published prices, on every change to the product.
Held to its own rules by test
That charges add up to totals, that a missing charge is never zero, and that a Partial option is never ranked.