Hi, I have some suggestions based on different scenerios. As described in the question the 2 Y's we are looking at here is Cost effictiveness Number of CR's Definitely these would be the end objectives when you are trying to improve your overall syste,. However I would suggest you to break up the process in to sub process and then go about optimizing each process for cost and output. To accomplish the same the first we need to analyse the system for which you are gettting the CR's. Lets Say your the process for which you are getting the CR is called Process 1 and there are 4 sub parts to the same : Process 1 A Process 1 B Process 1 C Process 1 D Now we need to analyse the following two: 1. Out of these processes, which sub process is responsible for the maximum number of CR's 2. Out of these processes, which of the processes is responsible for most critical and Cost Consuming CR's (Since you dont have client data available, you may go ahead with data that you have) Once you have identified these 2 Sub processes. You may perform Cause Effect and find out what to improve. Sigma Level Calculation: Here again we have 2 Scenerios: 1. Do you want to calculate the sigma level of the process for which CR's are coming and would keep the same Y's 2. Do you want to calculate the Sigma level of your CR handling system. Scenerio 1:Do you want to calculate the sigma level of the process for which CR's are coming and would keep the same Y's: In this scenerio, you may decide your Specified limits and your mean and carry on the sigma level calulation deppending upon cost and no of CR. Again depends on how many Activities are there per process for which you are calculating the same. Your Defects will be No of CR's outside the specified limits and Cost incurred on the same for a specified period more than specified running cost. Scenerio 2: Do you want to calculate the Sigma level of your CR handling system. : For this you may need to perform separate analysis on whether the task is being performed within the TAT assigned for a particular criticality. Here your defect would be tasks not being completed in assigned TAT. Customer Cost Parameter: This is something you may have to base on estimates if there is no way to get the correct data. Here you may not assign the actual figures, however you may measure the respective cost: e.g. for a process if it takes X manhours of a person working at $Y/Hr total cost would be $X*Y in the same way for another process if it takes more man hours but lesser paid manpower the cost would look like this: $(X+1)(Y-2). Later you may assign a value to X and Y and can find out what is more time cosnuming and cost consuming and may carry on your analysis. This is an idea provided for you to start. A project may not be based on this. Hence this may just give you a direction to start in but may not lead you to the end. Please refer project leads for the same.