I am running a project for transportation.. I have to reduce the transportation cost. I have a baseline created with % of freight spent to sales value. The problem is multiple location and multiple mode of transport and multiple product lines that affects the weight and utilization factor. Thus I have taken grouping as months, since these variables are there every month. Thus X bar chart was drawn for the baseline than using a I MR chart with individual data points. I have close to 50 data pts per month.. Thus I MR goes out of control limits but x bar S chart is within limits.. Is this the rt way to proceed.

Hi Kirthiga, 

 

Good question. I will need to know few things before answering your question. 

1. Are you taking this up as a Lean Six Sigma project?


2. If yes, is it a DMAIC or a DMADV project?


3. Why are you doing control charting? As a part of Measure phase or Control phase? 

Best Regards, 

VK

Its a DMAIC project and control chart is being done to draw the baseline and from there to define the goal as part of the charter.We usually take the mean from the control chart as the baseline. If you have Minitab 16, I can send the reference file

I-MR chart requires a test of normality and your data may be Non - Normal. It is okay to go with X bar for base-lining purpose.