Individual Absence Rate Velocity Formula
Learn how to calculate an individual's absence rate, percentage-point change, monthly velocity, and relative rate change across two periods.
This calculator compares recorded absence as a share of scheduled working days or shifts in two periods. It standardizes each period using scheduled time, then estimates the average monthly direction and speed of change between the period midpoints.
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Monthly Absence Rate Velocity
Where:
Calculate the absence percentage for each period, find the difference in percentage points, and divide that difference by the number of months between the periods.
Variables Explained
| Variable | What It Means | Unit |
|---|---|---|
| currentAbsenceDays - Current-period absence days | Scheduled working days or shifts lost to recorded absence in the most recent period. | days |
| currentScheduledDays - Current-period scheduled days | Working days or shifts the individual was scheduled to work in the current period. | days |
| previousAbsenceDays - Previous-period absence days | Scheduled working days or shifts lost to recorded absence in the earlier period. | days |
| previousScheduledDays - Previous-period scheduled days | Working days or shifts the individual was scheduled to work in the earlier period. | days |
| comparisonPeriodMonths - Time between period midpoints | The number of months separating the midpoints of the current and earlier periods. | months |
| currentAbsenceRate - Current absence rate | The percentage of current scheduled time lost to absence. | percent |
| previousAbsenceRate - Previous absence rate | The percentage of earlier scheduled time lost to absence. | percent |
Step-by-Step Calculation
Calculate the current absence rate
Divide current absence days by current scheduled days and convert the result to a percentage.
currentAbsenceRate = (currentAbsenceDays / currentScheduledDays) * 100
Calculate the previous absence rate
Use the same method for the earlier comparison period.
previousAbsenceRate = (previousAbsenceDays / previousScheduledDays) * 100
Find the percentage-point change
Subtract the earlier rate from the current rate. This is a percentage-point change, not a relative percentage change.
absenceRateChange = currentAbsenceRate - previousAbsenceRate
Calculate monthly absence rate velocity
Divide the rate change by the months between period midpoints. A negative result means the rate has fallen on average.
absenceRateVelocity = absenceRateChange / comparisonPeriodMonths
Calculate the relative rate change
This expresses the change relative to the earlier rate. The minimum denominator prevents division by zero, but a very low prior rate can still produce a large result.
relativeRateChange = ((currentAbsenceRate - previousAbsenceRate) / max(previousAbsenceRate, 0.01)) * 100
Example: absence rate rising across two three-month periods
Current absence rate
(5 / 60) * 100
8.33%
Previous absence rate
(2 / 60) * 100
3.33%
Absence rate change
8.33 - 3.33
5.00 percentage points
Monthly absence rate velocity
5.00 / 3
1.67 percentage points per month
Relative rate change
((8.33 - 3.33) / 3.33) * 100
150.0%
Final Result
The current absence rate is 8.33%, up 5.00 percentage points from 3.33% previously, with an average monthly velocity of 1.67 percentage points per month.
Assumptions
- ✓Absence days and scheduled days use the same unit, such as workdays or shifts, in each period.
- ✓The two periods use a consistent definition of recorded absence.
- ✓Scheduled days exclude non-working days and should reflect the time the individual was expected to work.
- ✓Monthly velocity is an average change between period midpoints, not a prediction of future absence.
- ✓The calculation summarizes records only and does not explain the reasons for absence.
Limitations
- !A result based on a small number of scheduled days can move sharply after one absence day.
- !Different shift lengths are not adjusted when days or shifts are used instead of hours.
- !A two-period comparison may not reflect longer-term patterns or seasonality.
- !A high relative change can be misleading when the earlier absence rate was close to zero.
- !Results may differ if records are incomplete or schedules were recorded inconsistently.
Common Mistakes to Avoid
Using calendar days instead of scheduled working days or shifts.
Comparing periods with different absence definitions or recording practices.
Reading a percentage-point change as a relative percentage change.
Entering the length of one period instead of the months between the two period midpoints.
Treating a positive or negative velocity as an explanation for an individual's circumstances.
Related Formulas
Frequently Asked Questions
How is individual absence rate velocity calculated?
It is the current absence rate minus the previous absence rate, divided by the months between the two period midpoints.
What does a negative absence rate velocity mean?
It means the recorded absence rate fell on average between the earlier and current periods.
Is absence rate change measured in percent or percentage points?
The direct difference between two rates is measured in percentage points. Relative rate change is measured as a percent of the earlier rate.
Why does the formula use scheduled days?
Scheduled days provide the relevant denominator because they represent the time the individual was expected to work.
Can I compare periods with different numbers of scheduled days?
Yes, provided the periods use consistent records and definitions. Each absence total is divided by its own scheduled-day total.
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