jabenir, There is one fundamental question you have to answer before calculating Capability Indices: Is your process in statistical control? If the process is not in a "reasonable degree of control", then Capability Analysis is meaningless. As Dr. Wheeler says in one of his books: "What can be said for the capability of a process not I statistical control? Not much!"

Other questions that need to be answered BEFORE a Capability Analysis: Is the data you presented in time order? If not, what is the order and what does a Runs Chart and/or Process Behavior Chart look like? Can you determine defect rates for discrete periods of time with rational sub-grouping?

Steve