Cp Cpk % out of tolerance

Cp

Calculates the Cp value of a column

Formula

With a higher Cp value the data set is better within tolerance. When the mean is adjusted to the nominal value.

Cpk

Calculates the Cpk value of a column

Formula

With a higher Cpk value the data set is better within tolerance.

Cpk	sigma level	% out of tolerance
0.33	1	31.73
0.66	2	4.55
1.00	3	0.27
1.33	4	0.01
1.66	5	0.0001
2.00	6	0.0000002

% out of tolerance

Calculates how much % of the data set is statistical out of tolerance.

Formula

interpolate the value out of the z table.
interpolate the value out of the z table.

% out of tolerance is

Legend

= Mean
s = STDEV
USL = Upper specification limit
LSL = Lower specification limit
sigma level = http://en.wikipedia.org/wiki/Three_sigma_rule

External links

• http://en.wikipedia.org/wiki/Process_capability_index
• http://en.wikipedia.org/wiki/Three_sigma_rule