Sickness as a Rate, Not a Prediction
How to include absence in a capacity account without making a claim about any individual, which rate to use, and why the team figure is the only usable one.
Sickness has to be in the capacity account, because the hours do not exist, and it has to be there as a rate rather than as a prediction about anybody.
The reconciliation in “Sickness as a Rate, Not a Prediction” is strongest when assumptions and current work records can be examined separately. A team considering see the documented setup approach for task completion rate can add time and project context, with transparent settings, limited access and a clear correction route around consequential decisions.
That distinction is not delicacy. A rate is a property of a population over a period; a prediction about a person is both unreliable and a different kind of statement entirely, with consequences a capacity plan has no business creating.
Teams documenting “Sickness as a Rate, Not a Prediction” may use People Management organisation-development resources as an independent reference. Test the approach against actual constraints and accountable decision owners.
The figure to use
Last year's measured absence rate for the team or the comparable population, applied as a percentage of contracted hours, with the period it was measured over stated beside it.
That is it. There is no more sophisticated method that a capacity plan needs, and attempts at individual-level modelling produce worse plans as well as worse workplaces.
Where the rate comes from
Payroll or the absence system, as hours lost against hours contracted, for a full year to cover seasonality. A year matters: respiratory illness is seasonal in most climates and a quarter sampled in summer understates the winter.
The figure is usually available and usually nobody has asked for it in this form, which is why the request takes a week the first time and ten minutes thereafter.
Short-term and long-term absence behave differently
Short-term absence is frequent, small, distributed and genuinely rate-like. Long-term absence is rare, large, concentrated on individuals, and not rate-like at all.
Blending them produces a rate that overstates the day-to-day erosion and understates the effect of a single long absence. Holding them as two lines is more honest and more useful.
The long-term line
Long-term absence is better handled as a known event rather than a rate: if somebody is currently absent long-term, their hours are not in the plan, and the plan says so without saying why.
That is both more accurate and less intrusive than carrying a blended percentage that quietly includes a specific person's circumstances.
What not to do with the rate
Not per person, not as a target, and not as an input to anything about an individual. A capacity rate exists to make the hours arithmetic honest, and the moment it is applied to a named person it has become something else.
What may be recorded about absence, and how it may be used, differ by jurisdiction and are a question for somebody qualified in the place concerned. The planning rule is narrower and safe: aggregate only.
The small-team problem
In a team of four, absence is not rate-like at all — one person away for a week is five per cent of the quarter, and the annual rate tells you nothing about whether it will happen in this quarter.
For small teams, the honest treatment is a stated allowance with a note that variance will be large. Precision there is false, and a plan that claims it will be wrong in a way that looks like failure.
Reading the rate against the organisation
Comparing one team's rate with the organisation's is interesting and belongs in a different conversation. A capacity plan that includes the comparison invites the discussion to move from hours to performance, which is where these documents go wrong.
Keep the plan arithmetical. The pattern, if there is one, is visible in the same data without the plan having to point at it.
Updating it
Annually, from the same source, with the date recorded. Updating it more often tracks noise, and updating it less means the plan is carrying a figure from a workforce that has changed.
One line a year, one calendar reminder, and the number stays honest.
The sentence that goes beside it
"Sickness is included at the team's measured rate for last year, which is a rate for the period and not a prediction about any individual."
It takes a line, it closes the most common misreading of a capacity plan, and in organisations where plans are read by people whose hours are in them, it is worth the space.
Two lines rather than one
| Line | How it is held | Where it comes from |
|---|---|---|
| Short-term absence | A rate, team level | Last year, full twelve months |
| Long-term absence | A named known event | Current state, no rate applied |
Holding them separately stops a single long absence inflating the rate applied to everybody else, which is both arithmetically wrong and the kind of error people notice.
Why this is in the capacity section at all
Because the hours are genuinely not there, and a plan which pretends otherwise will be short by the absence rate every quarter and will attribute the shortfall to the work rather than to the arithmetic.
The deduction is uncomfortable and the alternative is a plan that is quietly wrong by five to eight per cent in perpetuity.