QualityAdvisorsponsored by PQ Systems
Quality Assurance SPC statistical process control software for an organization’s continuous improvement program.
Home
Library
Classroom
Forum
Resources
About
PQ Systems
 
home > sqc > interpretation

Untitled Document

Too close to the average

Notice that nearly all the points lie close to the average. This pattern could be caused by a number of circumstances, including:

  • Edited data

  • Reduced variability without recalculation of control limits

When this pattern occurs, try to establish why. Is this apparent improvement genuine? Can the improvement be maintained? If the improvement can be maintained, then the control limits need to be recalculated. Although the data looks more stable than normal, this condition is referred to statistically as “unstable.”


Chart made by SQCpack. Visit www.sqcpack.com for information.

See also:
>Any nonrandom pattern
>Too far from the average
>Cycles
>Trends
>Clusters
>Sawtooth
>2 of 3 points beyond 2 sigma
>4 of 5 points beyond 1 sigma