Describing performance data by its distribution, perhaps summarized by the mean and standard deviation, is fine as a first step but is not much use in itself. We want to know what factors drive high and low performance. We want to see how our management interventions affect performance. We want to investigate and quantify performance differences across market segments.
Here are a few more specific examples.
Questions such as these motivate the methods and ideas in the chapter. The key idea is breaking data up into meaningful subgroups and comparing the performance across the groups.
But there is another issue that we have completely ignored up to now. Not all business performance can be summarized in a single number. It is part of the complexity of modern work that we ...