Another new feature we’ve added to GainSeeker Suite v8.2 is the Normal Probability Plot (NPP).
The NPP gives useful visual representation of data to help you assess whether the data are normally distributed. If they are normally distributed, they will be plotted close to the diagonal line, as shown below.
Other types of distributions have different curve characteristics. For example, left skewed data will plot by bending downward and to the right of the diagonal line, like this:
The other thing that is really cool about the Normal Probability Plot is that it gives you an easy-to-see visual answer to the question: Can we meet our target? You can get to this information by displaying specifications on the chart, and then looking at where the diagonal line crosses those specifications. You can see that by looking at the horizontal red lines on the chart below:
What this is telling us is that in this process, you’re below specification about 10% of the time. It also says that you’re above specification about 10% of the time. And if this data is coming from a stable control chart, you can predict that as long as the process doesn’t change, you’ll continue to produce those same results.
I wonder if this tool would be especially valuable in non-manufacturing applications. What if you used it for the cycle time for closing calls in a call center? Or perhaps sales targets and results? Or what about Net Income? I envision this chart on a KPI Dashboard of key business metrics.