周末统计问题(16): 定量数据的变异程度如何测量？ / 开普饭

统计问题（16）：定量数据的变异程度如何测量？

*请大家在看问题答案解析之前，先“投票”，也看看大家的结果

Question

Which, if any, of the following are measures of spread?

a) Mode

b) Interquartile range

c) Skewness

d) Variance

Answer

When presenting numerical data it is useful to give an idea of the range of values covered by the data. The maximum and minimum values would define the entire range, but would not describe how typical these values would be. Measures of spread provide a summary of how spread out observations typically are.

The interquartile range is described by the bottom and top values that contain the middle 50% of the observations in the set of data. 25% of observations fallbelow this range and 25% above it.

Variance is the average of the square of all the differences between individual observations and the mean. Taking the square root of this gives the familiar standard deviation.

The mode is the most frequent value in a set of data and does not measure spread.

Skewness is a measure of the lack of symmetry in a set of data and does not measure spread.

中文解释：

在展现数值数据时，有必要度对数据的分布范围有所了解。最大值和最小值将定义整个范围，但不会描述这些值的典型程度。数据分布程度提供了观测值的的大致分布范围。

四分位数范围由包含数据集中观察值中间50％的最低和最高值描述。所有观察中， 25％的观察值低于此范围，而25％高于此范围。

方差是各个观察值与均值之间所有差异的平方的平均值。取平方根给出熟悉的标准偏差。

众数是一组数据中最频繁使用的值，并且不测量变异程度。

偏斜度是一组数据对称性的度量，并且不度量变异程度。

所以答案是选择 BD

原文出处：BMJ杂志

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