2.4.5.1. Resolution

2. Measurement Process Characterization
2.4. Gauge R & R studies
2.4.5. Analysis of bias

2.4.5.1. Resolution

Resolution

Resolution (MSA) is the ability of the measurement system to detect and faithfully indicate small changes in the characteristic of the measurement result.

Definition from (MSA) manual

The resolution of the instrument is

if there is an equal probability that the indicated value of any artifact, which differs from a reference standard by less than

, will be the same as the indicated value of the reference.

Good versus poor

A small

implies good resolution -- the measurement system can discriminate between artifacts that are close together in value.

A large implies poor resolution -- the measurement system can only discriminate between artifacts that are far apart in value.

Warning

The number of digits displayed does not indicate the resolution of the instrument.

Manufacturer's statement of resolution

Resolution as stated in the manufacturer's specifications is usually a function of the least-significant digit (LSD) of the instrument and other factors such as timing mechanisms. This value should be checked in the laboratory under actual conditions of measurement.

Experimental determination of resolution

To make a determination in the laboratory, select several artifacts with known values over a range from close in value to far apart. Start with the two artifacts that are farthest apart and make measurements on each artifact. Then, measure the two artifacts with the second largest difference, and so forth, until two artifacts are found which repeatedly give the same result. The difference between the values of these two artifacts estimates the resolution.

Consequence of poor resolution

No useful information can be gained from a study on a gauge with poor resolution relative to measurement needs.