http://www.qualitymanagers.com/taxonomy/term/112/0 Variation caused by recurring system-wide changes such as seasonal changes or long-term trends. en http://www.qualitymanagers.com/structural-variation <p>Variation caused by recurring system-wide changes such as seasonal changes or long-term trends.</p> Structural Variation Wed, 15 Nov 2006 16:26:55 -0500 joseph 20 at http://www.qualitymanagers.com