When is the stack plot most useful? A. A stack plot is best used with time-series data. It is most useful when the trends of that data need to be shown over time and the difference between categories is not important. B. A stack plot is best used with ordinal data. It is most useful when the data rankings are more important than the actual data values. C. A stack plot is best used with categorical data, so that each category can be shown on the same plot. It is most useful when the difference between categories is important. D. A stack plot is best used with cumulative or relative-frequency data, including time-series data. It is most useful when the total of the data sets is important.
The correct answer and explanation is:
Correct Answer: D. A stack plot is best used with cumulative or relative-frequency data, including time-series data. It is most useful when the total of the data sets is important.
A stack plot, also known as a stacked area chart, is a graphical representation that shows multiple data series stacked on top of each other. Each series represents a part of a whole and is layered in a way that the upper series sits on top of the ones below. This format allows viewers to see both the individual contribution of each category and the total value over time.
The primary use of a stack plot is with time-series data where each category’s cumulative contribution to the total is significant. It effectively illustrates how various components evolve and how they collectively influence the total. For example, stack plots are ideal for displaying how different sources of energy contribute to total energy production over several years. They help in observing both the individual growth or decline of categories and the overall trend of the dataset.
Cumulative or relative-frequency data suits this visualization well because the chart shows how different segments stack up to form a whole. When the total value at each time point matters, the stacked format ensures that this total is clearly visible, while also maintaining visibility of individual segment trends.
In contrast, stack plots are not suited for categorical or purely ordinal data where time and cumulative values are not a factor. They also become less effective when precise differences between segments are more critical than observing total trends.
Therefore, the correct context for using a stack plot is when analyzing cumulative or relative frequencies over time and when understanding the whole and its parts is important to the data interpretation.