Teams are usually in a big hurry to make an improvement in an under-performing process because there’s some degree of unhappiness or pain (usually financial) associated with that process. The sooner the process improves, the sooner the pain goes away. However, in the rush to move the needle a little in the right direction many teams fail to establish a performance baseline for their current process.
On the surface this is bad because without an understanding of the current state you won’t know if you’ve actually made any improvement. If your process is unstable and subject to special causes of variation, it’s impossible to tell whether the process has improved because of your deliberate action, or because of the influence of those special causes. In fact, those special causes may overwhelm and mask any positive effect of the intended process improvement.
I realize it may not always be practical to fully characterize a process and establish stability before trying to improve it, but if you can’t isolate and eliminate special causes then you can’t draw any conclusions about the success of your efforts.
