Gaddis G M, Gaddis M L
Department of Emergency Health Services, Truman Medical Center, University of Missouri, Kansas City 64108.
Ann Emerg Med. 1990 Mar;19(3):309-15. doi: 10.1016/s0196-0644(05)82052-9.
Descriptive statistics include measures of central tendency and variability. Measures of central tendency include mean, median, and mode. The mean is the arithmetic average of data from interval or ratio scales. The median reflects the 50th percentile score. The mode is the most frequently occurring value of a data distribution. Measures of variability include range, interquartile range, standard deviation, and standard error of the mean. The range describes the spread between the extreme values of data. Interquartile range is data included between the 25th and 75th percentile of a distribution. Standard deviation describes variability of data about the sample mean, while standard error of the mean helps describe the distribution of several sample means about a true population mean. Finally, confidence intervals, which are derived from the standard error of the mean, define an interval likely to include a true population value, based on sample statistical values and probability charceristics of data distributions.
描述性统计包括集中趋势和变异性的度量。集中趋势的度量包括均值、中位数和众数。均值是来自区间或比率尺度数据的算术平均值。中位数反映第50百分位数得分。众数是数据分布中出现最频繁的值。变异性的度量包括极差、四分位距、标准差和均值的标准误差。极差描述了数据极端值之间的跨度。四分位距是分布中第25和第75百分位数之间的数据。标准差描述了围绕样本均值的数据变异性，而均值的标准误差有助于描述多个样本均值围绕真实总体均值的分布。最后，基于均值的标准误差得出的置信区间，根据样本统计值和数据分布的概率特征，定义了一个可能包含真实总体值的区间。
