By Brian McKay
The other day was a great lesson for a 12-year-old on variability. A girl in her twenties was late for something and speeding in her Camry through traffic. She swerved through cars and signals as her impatience grew to get somewhere on time. It just so happened that she was taking the same route through town as the car the sixth grade girl was riding in to school. No matter how much the girl in the Camry rushed, the car the little girl was riding in always pulled up to the same light as her. Needless to say, the driver of the car taking the girl to school (me) was obeying the traffic laws and still getting to the same place at the same time until the frantic girl in the Camry decided to blatantly run a red light.
It was a great lesson in variability for a sixth grader. It was pointed out that the girl in the Camry was frantic and risking traffic violations but the variability inherent in the traffic lights and other drivers got her nowhere any faster.
Another recent episode saw a 15-minute outpatient surgery procedure for her relative turn into a 3 ½ hour wait. “Sorry”, was said multiple times by the office staff to the waiting girl to drive this relative home (again me). They said they had fallen very behind at the hospital surgical center. Falling behind had turned into a 3 ½ hour ordeal and a likelihood of ever again using that facility of zero.
Yes, something was said to the front desk agents about the lack of building variability into their scheduling. It is doubtful it will ever change though.
Businesses, especially start-ups, want to move as many customers through as possible in order to speed up cash flow. It’s necessary. The faster the cash comes in, the more viable the business. Unfortunately, we have seen that rushing doesn’t help and scheduling things too tight just loses customers.
Variability is always in play. The more variables in the process, the more it will fall behind. Only one bottleneck is needed to slow down every dependent event that comes after it. Once that happens, the backlog is only cleared when the inputs being introduced at the start of the line are slowed or stopped altogether. A common response is for the business to throw more capacity at the problem, but capacity costs money and often fails to alleviate the situation.
It doesn’t matter if it is a line at the bank or a production queue, the problem is always the same. If the waiting line is too long, customers leave. Throwing more capacity to compensate for the variability and keep them coming back, costs money and constrains profits. What the heck is a business to do?
If the girl in the Camry had gone the speed limit, she would have arrived at the same time and with less likelihood of getting a ticket. If the hospital would have created a schedule with compensation for variability built in, their patients would have been in and out much more quickly and far happier (one guy actually got off the hospital bed and left).
Slow down in order to get there faster. Yes, slow down.
Sure, the thought of pumping as many people through as fast as possible has great allure. Who doesn’t want more money now? If your business is a start-up, most likely you need more money now. Have you ever heard someone say, “I don’t know why that restaurant went out of business, there was always a huge wait for reservations.”?
Schedule in variability. As your company learns a range of times each process can take, allow for an average between the normal completion time and the worst case scenario for each operation. If x operation normally takes 20 minutes, but past experience has shown it could take as long as 40, you schedule 30. There might be times that operation x only takes 15 minutes, which is great. Customers love things on time.
Scheduling for a difference between the worst case scenario and the norm will get you there at the same time. Your commitments to customers will be better met, and you’ll be able to operate with consistent resources you can plan on. Basically, always under promise and over deliver.
If it sounds like this article is simply saying “build in some cushion”, then you have heard right. Maybe that is something that shouldn’t need to be said, but as the hospital story shows, most still don’t do it. If you have any control over the line or even a good idea of how it forms at certain times, cushion will save you money and enhance the customer experience.
This is just a very simple approach to scheduling. With more contingent events the variability and complexity grows. If The Goal by Eliyahu M. Goldratt, isn’t on your company’s reading list, add it. It is one of the finest business books you will ever read.
Slow down and get there faster.
Feature photo courtesy of losgofres, under Creative Commons Attribution-Noncommercial license
Brian McKay is a co-founder of zenruption and has his MBA from Boise State University. He really loves operations and looking at variability. Obviously he is not fond of long waits due to poor planning and subjects his daughter to lessons of variability every chance he gets. The zenruption team wonders about her future.