Stata中作图，Y轴的density（密度）、fraction（小数）、frequency（频数）、percent（百分比）分别代表什么意思？有时候还很容易混淆。写在这里备忘。




1. density scales the height of the bars so that the sum of their areas equals 1.

2. fraction scales the height of the bars so that the sum of their heights equals 1.


3. frequency scales the height of the bars so that each bar’s height is equal to the number of observations in the category. Thus the sum of the heights is equal to the total number of observations.


4. percent scales the height of the bars so that the sum of their heights equals 100