What is ‘First Pass Analysis’?

The phrase ‘First Pass Analysis’ refers to the process of having an initial look at your process output data (KPIs) in order to see what they can tell you about a process.

A First Pass Analysis is typically completed in the Measure phase, in order to help you to establish the baseline performance of the process and to understand how the process is currently behaving (ie. stable/unstable etc).

The two key components of a First Pass Analysis are a Time Series Plot and a Histogram:

  1. Time Series Plots are useful for understanding how a process is behaving over time. They show whether a process is stable (or not) and help to identify trends, outliers or other patterns that might be worth investigating.
  2. Histograms are useful for understanding the overall distribution in the output of the process. So, whilst they don’t show you things that are happening over time, they are useful in understanding the extremes of the process output (minimum and maximum) and where most of the process output occurs (the shape of the process distribution).

Times Series Plots and Histograms work together to provide a rapid assessment of process performance. Later on in a DMAIC project, and if necessary, in-depth techniques such as Process Capability and Statistical Process Control can then be used to provide a more statistical viewpoint.