I am putting a Control Chart together in excel and I am using the Chart in the manual as a reference. It is the first chart from appendix 1. As I was using this and several examples found elswhere I came to notice that the first subgroup does not calculate average or range in the SPC manual but all of my other examples do. What is the correct way to do this? I believe to get accurate control limits the first data should also be calculated. Am I missing something or is my cold medicine making me more of an airhead than usual?

Mark

Mark - I couldn't find the chart you are referring to. I don't seem to have an appendix 1.
Could you be looking at an Individual Moving Range chart?

Dave

Doh! It is appendix I as in H, I, J
Sorry about that. It is probably not true but I will blame the cold meds.

Mark

What is "the" manual?

I think that we are all referring to the SPC manual published by the AIAG in conjunction with the QS9000 set of manuals!

I will try and look into it for you.

I see it now Mike. I would guess the manual is off on this chart. If you are doing a 5 sample X-bar and R chart (the one indicated), the first sample group should be averaged and the range (high to low) should be figured. The chart you point out has no box to record these. If you are drawing a chart or making a master, you should correct this.

Dave

Sorry, meant Mark - typed Mike. Goes to show you, Typos happen especially before your second coffee.

Dave

Above reference from second printing,March 1995 (you may have diffeent version) on pages 32 and 34 shows intended use.

I agree that they made it confusing. Of course that does not take a whole lot with me!

The first column in the readings section is left blank and then all line up with the vertical plot point lines. Why did they do this?

Sorry, meant Mark - typed Mike. Goes to show you, Typos happen especially before your second coffee.

Dave
I thought it was wrong, but being a manual you never know if you maybe fell asleep during that part of the class or something. :lol:

By the way I get called Mike alot I knew who you meant.

Mark

Hi

I'm New here, but have been reading stuff here for months. Just thought I throw this out? A few years ago while working for another Company I had the opportunity to see an EXCEL SpreadSheet that Did SPC Graphing ?

All the operator did was enter in the measurements, the spreadsheet did all the calculations & ploting & Graphing!!

Has anyone seen a Copy of this tool,.?? know where I can get one,.??

Thanks for your help:D