2.2Organizing Qualitative Data
The number of times a particular distinct value occurs is called its frequency (or count)
Relative-Frequency Distribution:百分比
Note: Relative-frequency distributions are better than frequency distributions for comparing two data sets. Because relative frequencies always fall between 0 and 1, they provide a standard for comparison.
A pie chart is a disk divided into wedge-shaped pieces proportional to the relative frequencies of the qualitative data（the relative frequencies =percentages）
A bar chart displays the distinct values of the qualitative data on a horizontal axis and the relative frequencies (or frequencies or percents) of those values on a vertical axis. The relative frequency of each distinct value is represented by a vertical bar whose height is equal to the relative frequency of that value.The bars should be positioned so that they do not touch each other.