Comment by vivegi

Average by itself doesn't tell much. Average and standard deviation computed over multiple samples from the population tells a lot.

Learning about the various types of standard control charts is quite useful for data-based decision making and monitoring the health of a process.

Control charts and Pareto chart of root causes of defects are two of the basic tools one needs to establish 'basic stability' in a process. Basic stability is a requirement before working on improving a process.