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2 Calculating absence in order to manage headcount

23 Jan, 2020 11:28

Hi all,

Bit of a math question for you...

I work as a HR Administrator for a large manufacturing company and I was asked whether there was a method to work out how much absence cover the factory would need based off the absence % trends. The question was posed as follows:

If out headcount is (and needs to be) 700 and absence is 10% we need an additional 70 people to cover the loss. If 70 people are then off work the absence rate would be only 9%. If we then move to only provide 9% cover and we experience the same amount of people off, the factory will be short staffed.

Is there a way to calculate the absence rate and build in absence cover effectively?

Currently we measure available time by dividing the number of hours lost to sickness, non-sickness and holidays by the number of hours each employee was due to work in that same period. lost/available=absence.

Any assistance would be much appreciated!

Kind regards,

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Ray | 0 Posts

23 Jan, 2020 12:07

You need to assume that 10% of the extra 70 people will also be absent.... therefore your need is for 77 extra.
In the real world it will depend on which specific jobholders are absent at any one time, and the degree of multiskilling you have
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Robey | 0 Posts

23 Jan, 2020 12:17

Ooh, what a *very* interesting question. I do love a bit of maths and statistics.

Assuming your industry and workforce has a more-or-less stable absence rate (which is a big assumption, but let's keep it simple) of 10%, then of a 700-person workforce you'll have 70 absences. If you need a minimum of 700 people on the line to cover your workload, therefore, you need to overstaff such that 90% of your workforce is 700 people. That means that you need to have an average headcount of 778 staff. The absence rate won't change because you've got more people. So with 778 staff and an average absence rate of 10%, you'll have an average attendance of 700.2 people per day.

The formula - which took me far too long to work out - is:

s = am/(100-a)

Where s is the additional staff you need to hire, a is the absence rate expressed as a percentage and m is the minimum number of staff you need to have on the shopfloor to meet your output requirements.
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