Forecasting Abandoned Calls

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Forecast and Demand Analyst


I've been tasked with forecasting abandoned calls by interval. I realise its not normal practice, but have been told it has to be done!

Anyone have a good "non erlang" formula (and an erlang) way of doing it? I don't have a wfm system and my erlang availability is sporadic on our network.

RP Analyst

use the abandon formula in erlang

=abandon(no.agents,abandontime,calls per hour,aht)

if I remember correctly this gives you abn % which is a % of the forecasted calls (forecast*abn %) will give you the number of calls. if you are using 30 min intervals remember to multiply your 'calls per hour' by 2

RP Analyst

should have said that you will need to calculate the abandon time first if you don't keep records of that already, average time to abandon

Forecast and Demand Analyst

Thanks Mike, I think i've got it working now. Just need to try and figure out whether I can do a daily figure without a 15min breakdown too.

RP Analyst

hi laura, are you familiar with sumproduct in excel ou can use this then divide by the total calls

=sumproduct(abn% range,calls range)/totalcals

Forecast and Demand Analyst

Thanks Mike, i'm just getting my head around sumproducts. I was wondering whether there is a way of getting an abandoned figure without the need to break it down by interval. Will the =abandon(no.agents,abandontime,calls per hour,aht)formula work for a whole day rather than a 15/30min interval?

RP Analyst

you need to do this by interval, as it uses he number of agents you have per 30 min / 15 mins

Looking to Achieve the Same Goal
Hi Mike,

I'm looking to achieve the same goal but i'm using the online Online Erlang Call Centre Staffing Calculator (Version 3.1 Beta)

how would I be able to use the abandon formula in erlang ??
=abandon(no.agents,abandontime,calls per hour,aht)


Issue with formula
If you are calculating abandonment for 15min intervals do you multiply the volumes and number of agents by 4 or just the volumes. Do you also divide it by 4 once calculated. I am having issues with the abandonment coming out at 100% which, would be impossible unless no agents were logged on?


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