The disease occurs in the hand, wrist, feet and other small joints, repeated attack, a symmetrical distribution.

该病好发于手、腕、足等小关节，反复发作，呈对称分布。

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In a symmetrical distribution, values are equally likely to fall above the mean as below it, and the most likely value, the mode, is equal to the mean.

从对称分布来看，分布在中间值上面的与下面的差不多是相等的，最可能的值，即mode，是与中间值相等的。

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As the dataset is not in a symmetrical shape, we can clearly rule out that a normal distribution model would not be a suitable choice.

由于数据集不是对称的，我们可以清楚地排除正态分布模型不是一个合适的选择。

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