# How to assess capability for parameters which has got either Min values or Max values

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#### raju9619

I work in a cable industry. Here all the parameters such as dimensions, conductor resistance, Tensile strength values are mentioned either in minimum values or Maximum values

Eg: .The standards Says

1."Tensile strength of the PVC shall me Min 12.5 N/mm²" which means any thing above 12.5 is OK.

2. Conductor Resistance of Cable Shall be Maximum 7.98 Ω/KM Which means anything less than 7.98 is OK

#### Jim G

##### Involved In Discussions
Re: How to do SPC for parameters which has got either Minimum values or Maximum value

Hi Raju
Cpk is an index which measures a process performance to its specification limits, relative to the natural variability of the process. Cpk tells you how the process is capable of performing in the future. Cpk is calculated using an estimate of the standard deviation using R-bar/d2. Remember, the calculation requires the process to be in a state of statistical control. You can have a good Cpk and still have data outside the specification.
Hope this helps
Jim G

#### bobdoering

Trusted Information Resource
Re: How to assess capability for parameters which has got either Min values or Max va

I work in a cable industry. Here all the parameters such as dimensions, conductor resistance, Tensile strength values are mentioned either in minimum values or Maximum values

Eg: .The standards Says

1."Tensile strength of the PVC shall me Min 12.5 N/mm²" which means any thing above 12.5 is OK.

2. Conductor Resistance of Cable Shall be Maximum 7.98 Ω/KM Which means anything less than 7.98 is OK