计算标准偏差
标准偏差（Standard Deviation，SD）是样本平均数方差的开平方，它反映组内个体间的离散程度。其计算公式为
SD = \sqrt{\frac{\sum_{i = 1}^{n}(x_{i}-\bar{x})^{2}}{n – 1}}
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，其中
二、基于标准误差计算误差棒
计算标准误差
标准误差（Standard Error，SE）表示的是抽样的误差。其计算公式为
SE=\frac{SD}{\sqrt{n}}
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，其中
三、基于置信区间计算误差棒
确定置信水平和相应系数
常见的置信水平有95%，对应的常数系数在大样本情况下约为1.96（不同的样本量和分布情况可能会有不同的系数值）。
计算置信区间
若基于标准偏差计算，置信区间的计算公式为
\bar{x}\pm z\times\frac{SD}{\sqrt{n}}
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