Which of the following describes the shape of a stable process in a histogram?

A stable process is typically indicated by a distribution of data that displays a consistent pattern over time, which is most commonly represented by a unimodal or bell-shaped curve when plotted in a histogram. This bell-shaped curve reflects a normal distribution where the majority of the data points cluster around the mean, with fewer points appearing as you move away from the mean in both directions. This characteristic suggests that the process is stable and consistently performing within expected limits, indicating control and predictability.

In contrast, a random shape would suggest variability and a lack of control within the process, which does not represent stability effectively. A multi-modal shape, which indicates multiple peaks, might suggest a process that is influenced by different factors or sources of variation, thereby demonstrating instability or the presence of various sub-processes. Lastly, a linear shape implies a consistent trend over time but does not account for the spread of data around the mean, which can obscure whether the process is stable or not. Therefore, the unimodal or bell-shaped curve best captures the essence of a stable process in a histogram.