Signature
A = H_m / (H_m + H_w)
| Inputs | Definition | Unit |
|---|---|---|
H_m | Hours of work missed in the past seven days because of health problems, including sick days, arriving late and leaving early (question 2) | hours in the recall period |
H_w | Hours actually worked in the past seven days (question 4) | hours in the recall period |
A | Absenteeism score from the WPAI, the share of scheduled work time lost to health problems | proportion from 0 to 1 |
|---|
Function
Absenteeism measurement and valuation function
Maps the time a worker is absent from paid work because of ill health, the usual hours worked and a value per hour to the share of working time lost and to a productivity cost. The value depends on the method: the human capital approach counts the whole absence, while the friction cost method counts only the period an employer needs to restore production.
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Implementations
Excel
WPAI absenteeism score
With hours missed for health in HoursMissedHealth and hours worked in HoursWorked, Excel returns the proportion of work time missed, or #N/A when both are zero.
=IF(HoursMissedHealth+HoursWorked>0,HoursMissedHealth/(HoursMissedHealth+HoursWorked),NA())
Assumptions
Employed respondents with some scheduled work
The score applies to respondents in paid work, and H_m plus H_w is greater than zero. It describes the seven days before the questionnaire, so a longer period is sampled with repeated administrations or a different instrument.
Self-reported hours
Both terms are self-reported. Agreement with employer or registry records is generally good but imperfect, and the direction of error varies between instruments and settings.
Worked examples
One week with six hours missed
A respondent missed 6 hours because of health problems and worked 34 hours in the past seven days. The proportion of work time missed is 0.15, or 15%. The figures are illustrative.
H_m = 6; H_w = 34; A = 0.15
Common errors
Dividing by hours worked only
Dividing 6 hours missed by 34 hours worked gives about 0.176 instead of 0.15, and the error grows with longer absence. The denominator is scheduled time, hours missed plus hours worked.
Counting hours missed for other reasons
Adding holiday or other non-health absence (question 3) to either term misstates the share of time lost to health. The WPAI records it separately and leaves it out of the score.
Sources
WPAI scoring for the general health version
Reilly Associates. WPAI scoring: Work Productivity and Activity Impairment Questionnaire, General Health version (WPAI:GH). Accessed 29 September 2026. WPAI:GH scores: percent work time missed due to health = Q2 / (Q2 + Q4), where Q2 is hours missed due to health problems and Q4 is hours actually worked, multiplied by 100; questionnaire items refer to the past seven days.
Validation of the WPAI instrument
Reilly MC, Zbrozek AS, Dukes EM. The validity and reproducibility of a work productivity and activity impairment instrument. PharmacoEconomics. 1993;4(5):353-365. Original description, validity and reproducibility of the Work Productivity and Activity Impairment instrument.
Canonical Identity
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