Quick Way To Time A Process

Understanding and measuring process time is one of the most important aspects of process improvement. Much of the waste (muda) in a process causes a process to take longer than it should. When a process takes longer, customers are waiting for their final products and services and people in the process are typically costing the company more money. After all, “Remember that time is money,” Benjamin Franklin.

However, timing a process can sometimes also be a time-consuming process. And, if time is money, then quickly getting a good understanding of process cycle time, when conducting process improvement, is imperative. Working with several Lean Six Sigma certification candidates, I often share a quick and easy timing process that uses Good Operator Estimates and Weighted Per Accomplishment Times (WPAT). These are techniques that I learned in my Industrial Engineering training in the U.S. Air Force.

This timing process can be used with any process — healthcare, manufacturing, administrative, you name it. It is quick and easy and takes considerably less time than holding a formal process timing study.

Good Operator Estimates

This is a two-step process. The first step is to identify the “good operators” in your process to interview. We do not want the best or the worst operators, as they will skew the timings. You also want more than one operator to interview, but you do not need any more than five.

You are going to interview these operators and get their process timing estimates. Make sure that the way you ask your interview questions is always the same. Write down your interview questions so they are asked exactly the same way to each operator. Write down their responses on your interview sheet. Here are the first set of questions:

• What is the average amount of time your process takes?
• What is the fastest (optimal) amount of time your process takes?
• What is the slowest (pessimistic) amount of time your process takes?

By themselves, these times mean very little and are not really representative of the actual process. There is a second set of questions that you need to ask:

• Out of 100% of the time, what percentage does the fastest (optimal) process time occur?
• Out of 100% of the time, what percentage does the slowest (pessimistic) process time occur?

Now for a little math. Add the fastest and slowest percentages together and then subtract the total from 100%. This is the percentage of time the average process time occurs. Below is an example.

Conduct this interview for every operator and record each set of results.

Weighted Per Accomplishment Time

Now, this is where the fun begins. See, when the operators are asked the above questions in the manner presented, it is hard for an operator to “game the system.” If you were to simply ask each operator, “How long does this process take?” you would get a timing estimate much closer to the slowest (pessimistic) process time of 10 minutes. This is indicative of Parkinson’s Law, where time will fill the space available and people will always stretch out the amount of time something takes to fill the space.

So, how do we get a more reasonable good operator estimate?

We turn this into a WPAT by applying some simple mathematics. Multiply each of the estimated per accomplishment times (optimal, average, and pessimistic) by the estimated percentage that it occurs.  Then, add these three “weighted times” together to obtain a final WPAT. See the below example.

As you can see above, the estimated WPAT from this operator, in our example, is 4.95 minutes. The last step in the process is to add all the operator WPATs together and divide the final number by the number of operators interviewed. Basically, obtaining an average (mean) of all the WPATs. By averaging out all the operator times, you get a much better final estimate.

By following this simple, quick, and easy method of process timing, you can gain a very good estimate of how long a process should take on average. And that is a quick way to time a process!

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