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Elevators and Escalators - What Do They Tell Us About Variance
Elevators and Escalators - What Do They Tell Us About Variance

What can Elevators and Escalators tell us about "Variance"

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For some people, ideas of planning are rather straightforward. They know planning is useful, but when there are too many variables and things are not predictable they do not plan or depend on planning. What really matters to them is whether they can do the right thing when you face the challenge. Period.
To a large extent I do not disagree with them. 
It is not hard to convince people that planning is critical to execution, but what is the use of a plan that most likely is going to fail? A plan is credible only if/when we have a good idea about and control over the activities of a project. Let’s say an activity “B” can only be started after another activity “A” is complete. To plan for activity “B”, we must have a fairly good idea how long “A” will take to finish. If “B” cannot be started because “A” is not finished as planned, a lot of time energy and money could be at stake. In planning language, unpredictability about cost or schedule of an activity is called “variance”. 
So what can be done about variance? The first step in that direction is to understand variance and its nature a little further. To understand variance, we have to find simple real life situations where we use different methods and achieve the same results but with different variances. That brings us to Elevators and Escalators.
Let’s say you want to go from the ground floor of a mall to a third floor restaurant. You can take the escalators or the elevators or even the stairs.  Let’s make a comparison of time it will it take if you take the escalator vs. if you take the elevator. You will see the time taken for getting to the third floor with the escalators will take a fairly consistent time. With the elevator the minimum time it takes may be lower than the escalator but there are so many variables during the use of an elevator during crowded hours that the time taken to reach the third floor may be very significantly every time. Sometimes it can take three or four times more than other times. But an escalator on any day at any time during lean or crowed hours will take a fairly predictable time.
As you can see an escalator always takes in passengers without wait, always moves in the one direction only, works in continuous mode and moves people between two pre designated floors. An elevator on the other hand takes in passengers only when it reaches the floor, moves in both directions, works in batch mode and serves all the floors. That is what makes the escalator-travel time between two floors consistently predictable.
Can we design our work processes and systems such that variance is inherently less (e.g. Like Escalators)?
If we can, then the plans that we draw will be more predictable and the  schedules that we promise will be more achievable.
Have a look at this video and listen to the adventure I had with my friend Praveen - trying to explain what "Variance" really is.
Last modified onSaturday, 10 August 2019 12:36
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