What is a key characteristic of a run in a run chart?

A key characteristic of a run in a run chart is that it includes one or more consecutive data points that are all on the same side of the median. This concept is crucial for identifying patterns or trends in the data over time. When a series of data points consistently fall above or below the median, it indicates a potential shift in performance or a change in the underlying process being measured.

This characteristic helps highlight stability or variability in the data, which can be instrumental in quality improvement efforts. Observing runs can lead to insights regarding the performance of a system and whether any interventions have had an effect. It is important to distinguish runs from mere clustering of data points, as runs specifically reflect a sequence of points that adhere to this criterion of being on one side of the median.

The other characteristics, while they might seem relevant, do not define a run clearly. For instance, the median value being included in every run is not required, as runs can exist without touching the median. Similarly, a run doesn't necessarily have to reflect a shift in trends; it simply highlights consistency in the data points' placement relative to the median. Hence, focusing on the sequence of data points relative to the median is what solidifies the identification of a run in a run chart