2.9: 相对频率直方图

The relative frequency depicts the proportion of data points that have each value. The frequency tells the number of data points that have each value. Like the histogram, a relative frequency histogram also has the same shape with a horizontal scale (the x-axis), but the vertical scale (the y-axis) is marked with relative frequencies (percentages of the whole) instead of actual frequencies. A relative frequency histogram is a graphical representation of a frequency distribution where the heights of rectangle bars indicate the frequency with data falling into the associated classes, while the bar's width and position indicate the various classes. Frequency histograms must be labeled with either class midpoints or with class boundaries. The purpose of this graph is to check the distribution of data.