Final answer:
The assertion that a segmented bar chart must have a y-axis in percentages to show independence is false. Segmented bar charts can use actual counts or other units, although percentages are common for comparison.
Step-by-step explanation:
The statement that a segmented bar chart used to show independence must have a y-value in percentages is false. A segmented bar chart is a graphical representation of categorical data where each bar is divided into segments that represent the proportion of parts to the whole. While it's commonplace to use percentages to show these proportions, the y-axis can also represent the actual counts or different units of measure. However, when comparing multiple groups, using percentages can help normalize the data, making it clearer to observe patterns of independence or association between categories.