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View Full Version : Xbar/R control chart help (possibly a simple question)


zitro
8th October 2008, 12:25 AM
Hi, I'm new to minitab and I'm having an issue. I am given a list of sample means which I compute in a minitab column. I am also given the corresponding sample ranges. There are 24 samples, each with n=5

So I go to "variable chart for subgroups", enter "5" for subgroup size, and this is where I have a problem: the chart has 5 points instead of 24, and I noticed that each point is a mean of 5 consecutive sample means. This is not what I want, I want a control chart for each sample mean.

I do not have this problem with attribute charts.

Miner
8th October 2008, 12:29 AM
Minitab expects the raw data (individual x's) to be entered instead of summary data (xbar's and R's). Minitab does have a macro (http://www.minitab.com/support/answers/answer.aspx?log=0&id=1073) available that will take summary data and create the chart.