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Math Is Hard

December 4, 2018

Well, the math isn’t hard, but sometimes explaining it can be.

I typically have a single report I’m responsible for every month in my job. It has multiple names depending on which group I’m sending it to. Let’s call it the “Lost Time Report (LTR).”

The report is pretty simply conceptually. We count up how many minutes our agents are on the phone each month. That’s not hard. We have reports for that.

It’s slightly more complex when you consider that we have multiple sites: Five to be exact. We also have multiple call types. But, not every site handles all call types. Some sites handle as few as three call types and other sites handle as many as ten call types. Only one call type is common to all five sites.

But, again, that’s all an automated report. Not complicated at all. Where it starts to get interesting is when something goes wrong: an outage.

During an outage, I have to keep track of which sites were impacted, which call types were impacted, when the outage started and ended, and how many agents were impacted.

Oh, and I have to decide who’s fault it is: my company or our client. Sometimes it’s our fault. Circuits go down. Computers crash. Power outages happen. We have multiple layers of redundancy for every critical system, but even despite our best efforts, occasionally we have an issue.

The client can also have an issue. They own all the tools, and phones.

The LTR report has to capture all of that at the end of the month. We have SLAs or Service Level Agreements around our availability. In other words, if we have too many outages for too long that are the fault of my company, we fail to meet our SLA and that triggers potential consequences.

My entire job can be described as keeping us as far away from those consequences as possible. And the LTR is where I document all of it.

The math isn’t hard. Suppose agents in our “Accounting” call type were scheduled for 250,000 minutes in November (25 agents for 10,000 minutes each.) If we have no outages, we are at 100% available. In formula format it looks like:

100% – ( 0 (lost minutes)/250,000 (scheduled minutes)) = 100%

If we have a 40 minute outage, the math changes to

100% – (1000 (25 agents for 40 minutes) / 250,000) = 99.6%

Obviously, longer outages mean lower percentages and we fall into the SLA consequences.

Of course, the client also has outages that impact them. We don’t have to use their calculations when I do the above math. So, if the client caused us to lose 1000 minutes in the account call type, the math would change to

100% – (0 (my company’s lost minutes) / 249,000 (250,000 – 1000 minutes of client time.)

A couple months ago we had a situation where the amount of minutes we lost due to the client’s issues was about equal to the amount of minutes we lost due to issue with our local IT infrastructure. I was trying to explain to my boss that the two amounts didn’t “cancel one another out.”

Why not? If we lost time because of us or because of them it shouldn’t make any difference, right? Lost minutes are lost minutes.

You don’t understand. Our minutes affect the numerator. Their minutes affect the denominator.

I don’t get it.

It’s easier when we do the math. Let’s assume we lost 1000 minutes of time because of local IT issues. As we showed above, the system availability would be 99.6% Now, let’s take that 1000 customer minutes out.

100% – (1000 (our minutes)/249,000 (250,000-1000 client minutes) = 99.6%

Okay, it’s actually, 99.5984%. But, no one will complain if we round it up to 99.6%.)

In fact, if we lost 1000 minutes, no amount of client minutes would push our percentage back above 99.6%. We could reduce that 250,000 to 10,000 and our formula would become

100% – (1000/10000) = 9%

Zero downtime is so much easier to work with. Math is hard.

Rodney M Bliss is an author, columnist and IT Consultant. His blog updates every weekday. He lives in Pleasant Grove, UT with his lovely wife, thirteen children and grandchildren.

Follow him on
Twitter (@rodneymbliss)
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LinkedIn (www.LinkedIn.com/in/rbliss)
or email him at rbliss at msn dot com

(c) 2018 Rodney M Bliss, all rights reserved

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