Quality Assurance & Quality Control Charting:

As part of the our Quality Management System, Lambton Scientific continually tracks analytical batch external reference data on posted 6-sigma QA/QC Charts. By looking at the following 7 statistical rules, we are proactively looking at trends. Our statistical rules are:

Zone Rules:

Zone rules signal an out-of-control point or situation when “n” subgroups in a row are inside (or outside) a “zone” defined relative to the center line (mean) and control limits on the chart. For 6-sigma control limits, the zone boundaries occur at multiples of one sigma. The following zone rules are used to access quality control data:

• 2 of 3 above 2/3 of Upper Control Limit - see Figure 1
• 2 of 3 below 2/3 of Lower Contol Limit - see Figure 1
• 7 above Control Limit - see Figure 2
• 7 below Contol Limit - see Figure 2

Run Rules:

Run rules signal an out-of-control situation when a certain number of subgroups in a row are increasing, decreasing or alternating. Trending is indicative of a systemic error. The following run rules are used to access quality control data:

• 7 increasing - see Figure 3
• 7 decreasing - see Figure 3
• 14 alternating around Control Limit - see Figure 4