How A Coverage Score Works
When you create a log in LogCheck, you assign it an expected frequency, which reflects how often a log ought to be checked (e.g. hourly, daily, weekly, monthly, etc.).
In the field, when engineers perform checks on a log, those checks comprise an actual frequency, or how often a log is checked in reality.
At a conceptual level, a Coverage Score tells you how closely a log’s actual frequency matches its expected frequency for a given period of time.
How It’s Calculated
A Coverage Score is calculated as the ratio of covered hours to total hours for a log during a given period of time.
Let’s say we have a log called ‘Boiler Stack Temperature’ that is due to be checked once every four hours. If we’re interested in calculating this log’s coverage for the day of April 1, then our calculation concerns a period of 24 total hours.
Continuing with this example, if our log gets checked once at 12:00 p.m. (on April 1), we consider the log to have 4 covered hours (when no check is due) between 12:00 p.m. and 4:00 p.m.
If this is the only check made on April 1, the ratio of covered hours to total hours is 4/24 or 16.6%.
Overlapping Coverage
If the log in our example was checked again before it became due (say at 3 p.m.), that check would only contribute 3 hours of additional coverage to April 1, since the first hour after the second check (from 3 p.m. – 4 p.m.) was already covered by the 12 p.m. check. In other words, logs don’t receive extra credit for overlapping coverage.
Returning to our timeline, the ratio of covered hours to total hours given the second check is 7/24 or 29.2%.
Coverage Score per logbook
A logbook’s Coverage Score for a given period of time is simply the average of its constituent logs’ scores during that period.
If a logbook contained 3 logs with coverages of 30%, 40% and 50% on April 1, the Coverage Score for the entire logbook on April 1 would be (30 + 40 + 50) / 3 or 40%.