Seven Points Trending is an SPC (Statistical Process Control) rule detecting systematic process drift when seven or more consecutive points show a consistent upward or downward trend.

What Is the Seven Points Trending Rule?

• Trigger: 7+ consecutive points each higher (or lower) than previous
• Signal: Process shift in progress, not random variation
• Action: Investigate before out-of-control condition develops
• Rule Origin: Western Electric / Nelson rules for control charts

Why Seven Points Trending Matters

Random variation rarely produces seven consecutive moves in one direction (probability <1%). This pattern indicates assignable cause requiring intervention.

<svg viewBox="0 0 485 302" xmlns="http://www.w3.org/2000/svg" style="max-width:100%;height:auto" role="img"><rect x="0" y="0" width="485" height="302" rx="12" fill="#0d1117"/><g font-family="ui-monospace,SFMono-Regular,Menlo,Consolas,&quot;Liberation Mono&quot;,monospace" font-size="14"><text xml:space="preserve" x="20" y="31.7"><tspan fill="#c9d1d9">Control Chart with Trending Pattern:</tspan></text><text xml:space="preserve" x="20" y="50.7"><tspan fill="#c9d1d9">UCL </tspan><tspan fill="#6e7681">─────────────────────────────────</tspan></text><text xml:space="preserve" x="20" y="69.7"><tspan fill="#c9d1d9">                              ●</tspan></text><text xml:space="preserve" x="20" y="88.7"><tspan fill="#c9d1d9">                            ●</tspan></text><text xml:space="preserve" x="20" y="107.7"><tspan fill="#c9d1d9">                          ●</tspan></text><text xml:space="preserve" x="20" y="126.7"><tspan fill="#c9d1d9">                        ●      </tspan><tspan fill="#6e7681">←</tspan><tspan fill="#c9d1d9"> 7-point upward trend</tspan></text><text xml:space="preserve" x="20" y="145.7"><tspan fill="#c9d1d9">                      ●</tspan></text><text xml:space="preserve" x="20" y="164.7"><tspan fill="#c9d1d9">                    ●</tspan></text><text xml:space="preserve" x="20" y="183.7"><tspan fill="#c9d1d9">CL  </tspan><tspan fill="#6e7681">───────────</tspan><tspan fill="#c9d1d9">●</tspan><tspan fill="#6e7681">──────────────────────</tspan></text><text xml:space="preserve" x="20" y="202.7"><tspan fill="#c9d1d9">         ●</tspan></text><text xml:space="preserve" x="20" y="221.7"><tspan fill="#c9d1d9">LCL </tspan><tspan fill="#6e7681">─────────────────────────────────</tspan></text><text xml:space="preserve" x="20" y="240.7"><tspan fill="#c9d1d9">    1  2  3  4  5  6  7  8  9  10  11</tspan></text><text xml:space="preserve" x="20" y="259.7"></text><text xml:space="preserve" x="20" y="278.7"><tspan fill="#c9d1d9">Points 3-9: Each higher than previous </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Trigger rule</tspan></text></g></svg>

Common Causes of Trending:

• Tool wear (gradual degradation)
• Chemical depletion
• Temperature drift
• Operator fatigue across shift