In Six Sigma we track stability using what is known as &quot;The 7 Run Rule&quot; [1]<p>Not only do you want to see spikes but also unusual activity that suggests further investigation is warranted.<p>[1] <a href="https:&#x2F;&#x2F;www.qimacros.com&#x2F;control-chart&#x2F;stability-analysis-control-chart-rules&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.qimacros.com&#x2F;control-chart&#x2F;stability-analysis-co...</a>