Question

Suppose you are explaining the importance of variation to a friend. Using examples for both common cause and special cause variation, explain the difference between the two types of variation.

Answer 1

Common cause variation is predictable though sometimes it's difficult to predict since it's not always obvious. Special cause variation is not predictable.

Common cause variation does the most harm to our process. But special cause variation has a huge impact on the process .

Example:

Common cause variation according to pizza delivery times can be factorised as

1. Higher order volume around weekdays and weekends

2. Higher order volume during special promotion

3. Longer drive times in bad weather etc.

These all are predictive issues that can be remedied proactively

Special cause variation: suppose someone stole all the wheels from my delivery vehicles. I wouldn't purchase and store a spare set of tires for every car in our delivery fleet on the off-chance that they might be stolen again sometime in the future. But that's what happens when people try to solve special cause variation