供应商业绩符合正态分布吗？？

各位大虾，

昨晚，我把公司今年对供应商业绩的评估（上半年，下半年各一次）分别做了Symmetry分析，发现结果都不线性的。所以，我的问题来了
1。供应商业绩（分数）是不是正态分布？
2。如果不是，请问该是什么分布？
3，如果是，请问什么原因导致我司的数据不是正态分布？

Thank you.


Symmetry plots can be used to assess whether sample data come from a symmetric distribution. Many statistical procedures assume that data come from a normal distribution. However, many procedures are robust to violations of normality, so having data from a symmetric distribution is often sufficient. Other procedures, such as nonparametric methods, assume symmetric distributions rather than normal distributions. Therefore, a symmetry plot is a useful tool in many circumstances.