Need to Know Westgard Rules for Levey Jennings Charts?

Westgard rules are built into QI Macros so you don't need to memorize them.

Westgard Rules are used with Levey Jennings Charts in laboratories. They use a combination of traditional rules and some unique rules not used in other rule sets.

Draw a Levey Jennings chart using QI Macros:

  1. Select your data.
  2. Select Control Charts > Special > Levey Jennings on QI Macros menu.
  3. QI Macros does the math and draws the graph for you!

List of Five Westgard Rules

Westgard rules include Western Electric rules 1, 2, and 4, Nelson's Rule 5 and a unique rule #9.

  1. One point above UCL or below LCL (13s)
  2. Two points above/below 2 sigma (22s)
    *Westgard Rules state that 2 out of 3 points above/below 2 sigma can be Above AND Below the centerline*
  3. Eight points in a row above/below the center line (8x), note: this rule will catch 9-12x
  4. A trend of seven points in a row increasing or decreasing (7t)
  5. Four points above/below 1 sigma (41s) or two points in a row with one above and one below 2 sigma (R4s).

Westgard rule #9 is unique and is not included in other control chart rule sets.

Control chart rules available in QI Macros add-in for Excel

westgard control chart rules

QI Macros use Montgomery's Rules as the default. However, you can easily switch to the Westgard Rules using the QI Macros menu.

control chart rules menu

How to Change Control Chart Rules in QI Macros.

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