Measures of absenteeism typically consider the amount of time employees were unavailable for work in comparison to the number of hours available for work during the period under study. The definition of "unavailable" varies widely, however, and some companies include vacation and long term leaves whereas others count only unscheduled short-term leaves. Regardless of the calculation method, it is indisputable that absenteeism has a direct impact on productivity, simply because of the fact that employees are not present to perform their duties. Companies have also theorized that absenteeism represents an underlying problem within the work group.
List the specific absences you will include in the calculation. Decide whether to monitor scheduled absences -- such as vacation -- or only short term, unscheduled absences. Determine if you will include long-term or protected leaves -- such as those covered by the Family Medical Leave Act -- long-term disability leaves, pregnancy leaves or workers compensation leaves in the calculation.
Gather data on absences from a predetermined period, such as one calendar month or the previous fiscal year, for example. In some companies, automatically generated reports should be available through the time and attendance system. In smaller companies -- ones that do not rely on a computerized payroll system to process absences -- you will need to verify individual attendance records with each employee's supervisor.
Calculate the average number of employees on the books during the period in question. For example, if you are reviewing absenteeism for the prior fiscal year, calculate how many employees were on the books on the first of the month each month. Add those figures together and divide them by twelve -- the number of months -- to get the average employee population during the year.
Multiply the average number of employees (E) by the number of available work days (W) or hours, if you prefer to monitor absenteeism in hourly increments. Add the total number of days -- or hours -- lost due to absences during the predetermined time period (A). Divide this total by the number of employees multiplied by available work hours to get the overall absence rate, as follows: A / (E x W).
Perform the absenteeism calculation for different divisions, classifications of employees or regional offices, for example. Follow up if the absenteeism rate indicates an unusually high level of absence in a particular area.
Perform the absenteeism calculation regularly and compare the trend against past results to determine if there has been a significant change.