What is the difference between X Bar - R Charts and Average Chart?

Dear forum member,

i would like to seek opinion on the following:

1) I have some confusion about the use of X Bar - R Chart in SPC. What is the difference between X Bar - R Charts and Average Chart? Is it necessary to do it together at one time or can we choose to do any one of the chart at one time? .My c SPC checksheet showing only X Bar chart and Range Chart in its content and this has made me confuse because i am not sure whether Range Chart and Average Chart are referring to the same item or not? Please help to clear my doubt. Thank You.

xBar-R chart is a well understood term where I take sequential groups of data and plot their ranges and their averages and evaluate them on two separate charts. You should do both charts

However, I am unsure as to your use of the term "average chart". Could you give a context? My suspicion is that the average chart you are referring to is indeed a xbar chart, but I need more information to make that call.

Dear Sir,

i attached herewith the SPC checklist and SOP for your reference. Please give your comment based on my question. Also please advice me whether the
SPC Checklist is good enough to be used as statistical tool for inprocess control. Thank You

The first file, SPC checklist looks correct, standard for xbar - R. The second file would not open in Excel for me, said it was corrupted.

Sir,

i have uploaded the SOP in pdf . View attachment SOP for X bar and Average Chart.pdf

That is odd, I don't know why they would call they last page an average chart versus the previous xbar -R titles. This document is showing out of control criteria, which are the same whether or not you are talking the xbar chart, the Range, a c-chart, u-chart, or whatever.

Just to recap and confirm,are u telling me that the AVERAGE CHART not required for the inprocess line analysis. If so,can i just use X-Bar and Range Chart only as to measure inprocess? Please give your recommendation.

Muhd Firdaus said:

Just to recap and confirm,are u telling me that the AVERAGE CHART not required for the inprocess line analysis. If so,can i just use X-Bar and Range Chart only as to measure inprocess? Please give your recommendation.

Click to expand...

The purpose of the SOP file only appears to demonstrate what there are for examples of SPC signals. Use of the X-bar and R set of charts is sufficient for most applications.

You may need to move to different types of charts in some instances, such as tool wear, or if you specifically have a binomomial or poisson situation, but generally you can't go wrong with x-bar R.