# SPC Card for One Sample Size - Customer requires for all critical dimensions

#### Silvia12

##### Registered
Hello,
our customer requires for all critical dimensions using SPC card. We should use SPC card for one sample size and also for minimum and maximum (3 measurements on one sample - to find minimum and maximum on part).
For calculating AL, UCL and LCL we use Wincep.

Is it possible to use SPC card just for one measurement and also for minimum and maximum?

Thank you

Silvia

#### Bev D

##### Heretical Statistician
Super Moderator
what is the "SPC card"?

#### Silvia12

##### Registered
Statistical Process Control (SPC) is a method of quality control which uses statistical methods. SPC is applied in order to monitor and control a process.

#### Bev D

##### Heretical Statistician
Super Moderator
Thanks, I am fully aware of what SPC is. my question is what you mean by and SPC card.

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#### Steve Prevette

##### Deming Disciple
Super Moderator
I must admit I am also confused about this question. Usually I do SPC on a measurement, perhaps using two charts - Xbar and Range. But I'm not aware of a situation where you are doing SPC on the min and max.

#### Bev D

##### Heretical Statistician
Super Moderator
I must admit I am also confused about this question. Usually I do SPC on a measurement, perhaps using two charts - Xbar and Range. But I'm not aware of a situation where you are doing SPC on the min and max.

that would also be my next question. there is a way to min/max control charts: use a median chart for the location and the range for the dispersion chart.

#### bobdoering

Trusted Information Resource
I must admit I am also confused about this question. Usually I do SPC on a measurement, perhaps using two charts - Xbar and Range. But I'm not aware of a situation where you are doing SPC on the min and max.

X hi/lo-R chart uses min and max. Avoids the error one can have by ignoring within-characteristic error (as in a circular feature or length). But, it was designed for a specific distribution, as well as non-random variation.

Unfortunately, there is not enough information on the application to determine what technique is appropriate.

D

#### Darius

... we use Wincep.

Is it possible to use SPC card just for one measurement and also for minimum and maximum?

I checked on the net and found that WinCEP Plus 5 is used in Brazil (vtb.com.br) and Control Charts is translated to "CARTAS DE CONTROLE" in portuguese, so SPC Charts = SPC card

NO, if is just one measure, you cant use Hi/lo chart, the SPC chart for individuals is IxMR, or Individual and moving range charts. I don't see if your software supports it, but is most likely.

#### bobdoering

Trusted Information Resource
I checked on the net and found that WinCEP Plus 5 is used in Brazil (vtb.com.br) and Control Charts is translated to "CARTAS DE CONTROLE" in portuguese, so SPC Charts = SPC card

NO, if is just one measure, you cant use Hi/lo chart, the SPC chart for individuals is IxMR, or Individual and moving range charts. I don't see if your software supports it, but is most likely.

True, if it is one measurement you can't use high and low. But, if it is one feature (and we are having a translation issue), several measurements can be taken from that feature AND the process shows the correct distribution, you can use X hi/lo-R.

The software is not likely to be sophisticated enough to include the X hi/lo-R charting methodology. Many SPC software companies are not keeping up with this - even though it is over 10 years old.