As quality professionals, we frequently report such facts as proportions (percentages), process capability indices, averages and standard deviations as if we know what we’re talking about. But what’s our actual level of confidence? All of our observations and our understanding are based upon data or, more accurately, a sample of the universe that we’re attempting to describe. Just as the late astronomer Carl Sagan in his description of the universe as being made up of billions and billions of stars (more or less infinite) so is our opportunity to observe our “quality” universe. The magnitude of our astronomical universe did not deter Dr. Sagan’s desire to understand it. The size of our “quality” universe should not diminish our desire to understand it. We can’t observe our universe in totality, neither our astronomical or quality universe.

Just as Dr. Sagan sampled the universe, we need to sample the quality universe. However, it’s important to be careful in making absolute judgments regarding the nature of our universe.

By definition, a statistic is a value derived from a sample of a larger universe (our process or quality universe). All statistics are subject to error, and there’s no way to get around this. We can however recognize, acknowledge and report this error.

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