A WARNING ABOUT MEDIAN REACTION-TIME
A WARNING ABOUT MEDIAN REACTION-TIME
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DOI：
10.1037/0096-1523.14.3.539
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发表时间：
1988-08-01
影响因子：
2.1
通讯作者：
MILLER, J
中科院分区：
文献类型：
--
作者：
MILLER, J
当与正偏态反应时分布一起使用时，样本中位数往往高估总体中位数。高估的程度与反应时间分布中的偏斜量直接相关，与计算中位数的样本大小成反比。仿真表明，在小样本和高度偏态分布的情况下，高估可能接近50ms。中位反应时间偏差的一个重要实际后果是，当实验条件下的试验次数不相等时，不能使用样本中位数来比较实验条件下的反应时间。如果使用样本大小不等的中位数，则偏差可能会在条件中产生人为差异或掩盖真实差异。最近对提示和刺激概率效应的一些研究提供了这种潜在伪像的例子。
When used with positively skewed reaction time distributions, sample medians tend to over-estimate population medians. The extent of overestimation is related directly to the amount of skew in the reaction time distributions and inversely to the size of the sample over which the median is computed. Simulations indicate that overestimation could approach 50 ms with small samples and highly skewed distributions. An important practical consequence of the bias in median reaction time is that sample medians must not be used to compare reaction times across experimental conditions when there are unequal numbers of trials in the conditions. If medians are used with unequal sample sizes, then the bias may produce an artifactual difference in conditions or conceal a true difference. Some recent studies of cuing and stimulus probability effects provide examples of this potential artifact.