Two forms of control chart designs: a) those based on X-bar and R, and b) those based on T and sigma-naught. The formulas for building these charts are virtually the same, and so we can expect the charts to look fairly similar. Or can we?
Discuss the appearance and usage you expect to see for a given process charted using both techniques. What are the similarities and differences? Are the differences affected by the underlying quality of the process being charted? Are there advantages of one approach over the other if our goal is to improve?