Observed performance for Normal Capability Analysis

Find definitions and interpretation guidance for every observed performance measure that is provided with normal capability analysis.

PPM < LSL for Observed Performance

PPM < LSL for observed performance is the actual number of parts per million (PPM) that have measurements that are less than the lower specification limit (LSL).

In this histogram, the red bars represent the measurements that are less than the lower specification limit in the sample data.

Interpretation

Use PPM < LSL for observed performance to assess the actual number of nonconforming items, represented in parts per million, that are below the lower specification limit in your sample data.

Lower values of PPM < LSL indicate greater process capability, relative to the lower specification limit. Ideally, few or no parts have measurements that are less than the lower specification limit.

PPM > USL for Observed Performance

PPM > USL for observed performance is the actual number of parts per million (PPM) that have measurements that are greater than the upper specification limit (USL).

In this histogram, the red bars represent the measurements that are greater than the upper specification limit in the sample data.

Interpretation

Use PPM > USL for observed performance to assess the actual number of nonconforming items, represented in parts per million, that are above the upper specification limit in your sample data.

Lower values of PPM > USL indicate greater process capability, relative to the upper specification limit. Ideally, few or no parts have measurements that are greater than the upper specification limit.

PPM Total for Observed Performance

PPM Total for observed performance is the actual number of parts per million (PPM) that have measurements that are outside the specification limits. PPM Total equals the sum of PPM < LSL and PPM > USL.

In this histogram, the red bars represent the measurements that are outside the specification limits in the sample data.

Interpretation

Use PPM Total for observed performance to assess the actual number of nonconforming items, represented in parts per million, that are outside the specification limits in your sample data.

Lower values of PPM Total indicate greater process capability. Ideally, few or no parts have measurements that are outside the specification limits.

You can also use PPM to estimate the percentage of conforming and nonconforming parts in your process.
PPM % Nonconforming Parts % Conforming
66807 6.807% 93.193%
6210 0.621% 99.379%
233 0.0233% 99.9767%
3.4 0.00034% 99.99966%

% < LSL for Observed Performance

% < LSL for observed performance is the actual percentage of parts that have measurements that are less than the lower specification limit (LSL).

In this histogram, the red bars represent the measurements that are less than the lower specification limit in the sample data.

Interpretation

Use % < LSL for observed performance to assess the percentage of nonconforming items that are below the lower specification limit in your sample data.

Lower values of % < LSL indicate greater process capability, relative to the lower specification limit. Ideally, few or no parts have measurements that are less than the lower specification limit.

% > USL for Observed Performance

% > USL for observed performance is the actual percentage of parts that have measurements that are greater than the upper specification limit (USL).

In this histogram, the red bars represent the measurements that are greater than the upper specification limit in the sample data.

Interpretation

Use % > USL for observed performance to assess the percentage of nonconforming items that are above the upper specification limit in your sample data.

Lower values of % > USL indicate greater process capability, relative to the upper specification limit. Ideally, few or no parts have measurements that are greater the upper specification limit.

% Total for Observed Performance

% Total for observed performance is the actual percentage of parts that have measurements that are outside the specification limits. % Total equals the sum of % < LSL and % > USL.

In this histogram, the red bars represent the measurements that are outside the specification limits in the sample data.

Interpretation

Use % Total for observed performance to assess the percentage of nonconforming items that are outside the specification limits in your sample data.

Lower values of % Total indicate greater process capability. Ideally, few or no parts have measurements that are outside the specification limits.

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