What does 'Track by Exception' refer to in tracking production?

'Track by Exception' refers to the methodology of only tracking variables that change during the production or operational process. This approach allows for a more efficient use of resources, as it focuses attention and data collection on significant deviations from the norm or expected values. By concentrating on changes, teams can quickly identify issues that could impact outcomes, reducing the noise created by tracking every single variable constantly.

In practical scenarios, this concept is beneficial in environments where many variables are stable or predictable. Instead of sifting through vast amounts of unchanged data, stakeholders can concentrate on the exceptions—those elements that require further investigation or action. This maximizes efficiency and allows teams to allocate their time and resources where they matter most.

The other options convey tracking methods that do not embody the 'Track by Exception' philosophy. Producing tracks with detailed data entails comprehensive monitoring without distinguishing between critical and non-critical information. Transmitting bars of data implies a method focused on data communication rather than specific changes or variations. Lastly, tracking all accessible units would involve monitoring everything without regard to whether changes are occurring, which goes against the concept of focusing on exceptions only.