frequency distribution

symmetrical distribution

• 定义：平均值两侧的频率相对于平均值镜面分布。
• Definition: A distribution in which the frequency of values above the mean are a mirror image of those below the mean.

skewed distribution¹⁾

• 定义：数据堆积在分布的一端，而另一端成为比较尖细的尾端。
• Definition: Data is piled up at one end of the distribution, and the other end becomes the thinner tail.

positively skewed

• 如左图所示，数据堆积在左侧，尾部在右的偏态分布。其尾端指向X轴的正数一端，故称正偏态分布。具有均值大于中位数的特点。
• As shown in the left figure, the data is stacked on the left and tailed on the right. Its tail is pointed to the positive end of the X-axis, and here came the name positive skewed distribution. It has a higher mean than median.

negatively skewed

• 反之，如右图所示，如果数据堆积在右侧，尾部位于左边，则该分布被称为负偏态分布。具有均值小于中位数的特点。
• As shown in the figure on the right, if the data is stacked on the right and the tail is on the left, the distribution is so called negatively skewed. It has a lower mean than median.
  • 具体参考集中量数与差异量数。
  • For more information,please check for the part of numbers of concentrations.

• 偏态分布反映了数据的非对称性。在处理时，需要采取一些特殊的方法，如对数转换、Box-Cox变换等。
• The skewed distribution reflects the asymmetry of the data. So some special methods should adopted when processing, such as logarithmic transformation, Box-Cox transformation, etc.

bimodal distribution

• 定义：数据分布中存在两个明显的峰值或高频率区域，即次数集中在两个分数，以致分布曲线出现两个隆起的峰。
• Definition:There are two distinct peaks or high-frequency regions in the data distribution, which means the number of times is concentrated in two fractions, resulting in two raised peaks in the distribution curve.

rectangle distribution

• 定义：一个分布中所有值都是相同频次
• Definition: All values in a distribution are of the same frequency.