Common causes should be addressed by your process. Projects can be affected by either common or special causes of variation, e.g., system failures, attrition, or improper schedule or budget. Special causes cannot necessarily be prevented or addressed through process changes. Therefore, if you want better and faster and cheaper, you will need a different process. Sequence and Means Sequence and means are the two elements of a process.
Sequence is simply the order in which things are accomplished.
Required - an order that must be followed, as demonstrated through precedence, i.e., putting on a second coat of paint requires that the first coat already be applied and cured. In software development, precedence has long shown it is best to start coding after the requirements are gathered. Discretionary - the order in which it is decided that something will be done. Past precedence and the availability of related means influence the sequence in which discretionary processes are executed. After sequence comes the means by which the steps or tasks will be carried out.