Question

Multiple data: Briefly describes how each of the following can be used to show multiple data sets: a multiple bar graph, a multiple line chart, and a stack plot. When is the stack plot most useful?

Answer 1

Multiple bar Graph:

Sometimes there are more than two sets of data to be compared in a bar graph. In that case, a multiple bar graph can be used. A multiple bar graph compares as many sets of data you want. The process for creating a multiple bar graph is just like creating any other bar graph, only you will have more colors to represent different sets of data.

Sometimes comparing data can also be done by comparing data sets across multiple different bar graphs. The difference is the data is split versus all being compared in one graph. Either method allows you to analyze and compare the data being displayed

The following is an example of a bar graph showing ice cream sales in the months of July and August.

Multiple Line graph

A multiple line graph shows the relationship between independent and dependent values of multiple sets of data. Usually multiple line graphs are used to show trends over time. In the graph, each data value is represented by a point in the graph that are connected by a line. In a multiple line graph, there are two or more lines in the graph connecting two or more sets of data points. The independent variable is listed along the horizontal, or x, axis and the quantity or value of the data is listed along the vertical, or y, axis. Lastly, the legend, or key, states what each line represents.

Example:

The graph below shows the absolute minimum and maximum temperatures in Celsius in Dubai for 2005. State three conclusions about the data.

Stack plot

Unlike a Multi-set Bar Graph which displays their bars side-by-side, Stacked Bar Graphs segment their bars of multiple datasets on top of each other. They are used to show how a larger category is divided into smaller categories and what the relationship of each part has on the total amount. There are two types of Stacked Bar Graphs:

Simple Stacked Bar Graphs place each value for the segment after the previous one. The total value of the bar is all the segment values added together. Ideal for comparing the total amounts across each group/segmented bar.

100% Stack Bar Graphs show the percentage-of-the-whole of each group and are plotted by the percentage of each value to the total amount in each group. This makes it easier to see the relative differences between quantities in each group.

One major flaw of Stacked Bar Graphs is that they become harder to read the more segments each bar has. Also comparing each segment to each other is difficult, as they're not aligned on a common baseline.

Example

Stack bar charts should be used only when you want to check relative differences between quantities in each group. Also Number of groups should not be more than 5 to 7.