The Moving Range Chart is a control chart of moving ranges. Moving ranges are range value of preceding successive observations. It is used to track the process variation and detect signs of special causes with subgroup size is equals to 1. The process standard deviation is estimated using average moving range with moving range equals to 2 as default.
At the Excel Menu (For Excel 2007, go to Add-ins first)
Choose ProcessMA > Control Charts > Variables Charts for Individuals > Moving Range
In Variable, select the column containing the data (Positive integer)
In Historical Standard Deviation, enter the population standard deviation, otherwise it will be estimated from the data (Optional, Numeric, >0)
In Control Limit Multiples, enter the position to draw the upper and lower control limits. Multiple entries must be separated by commas (Optional, Numeric, >0, Up to 3 multiples)
In Lower Limit Bound, enter the bound on the lower control limit (Optional, Numeric)
In Upper Limit Bound, enter the bound on the upper control limit (Optional, Numeric)
In Phase, select the column containing the phase indicators (Optional, >=2 distinct values)
In Method, choose the method of estimating sigma
In Moving Range Length, enter the number of observations used to calculate the moving range (Integer, >=2)
Check the various checkboxes to perform respective tests
Click OK
You are the manager of a technical help division. There have been complains that response time were getting slow and erratic. You collected several measurements on response time and you want to run the I-MR Chart to evaluate the situation.
Open data worksheet by choosing ProcessMA > Tools > Data
Choose ProcessMA > Control Charts > Variables Charts for Individuals > Moving Range
In Variable, select U - Response Time
Click OK
The process is stable as the data points are randomly distributed and lie within the control limits.
Copyright © ProcessMA