Welcome

What are you trying to do?

Something I need to watch regularly in engineering, manufacturing and quality.

Before you start. Monitors currently run from the command line rather than from a page. The engine works and is tested; the interface for setting them up is still being built, so this route is the least finished of the four.

Your path

Create the study

One study holds the whole series.

Chart it before you judge it

A control chart separates ordinary variation from a real change. Most month-to-month movement is noise, and acting on it makes a process less stable rather than more.

Set up a monitor

A saved analysis with a cadence. It re-runs and reports what moved, without claiming the movement is significant - two consecutive estimates are not independent samples.

Read the series, not the last point

Twelve points tell you what one never can.

What people in your field ask

In engineering, manufacturing and qualitythe full guide

Chart the process - establish stability - then and only then measure capability - test changes against it.

Is my process stable?control chart
Can it meet the specification?process capability
Which machine, shift or operator differs?one way anova
Two settings at once, and do they interact?factorial anova
How long until failure?kaplan meier

Watch for: Drawing control limits from the specification. That chart cannot show the process drifting inside tolerance, which is the reason to draw it.

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