想请教大神们，“The distribution of the variables was checked by Q-Q plots and when non-normal distribution was found, data
was ln-transformed to improve the normality”，这句话是什么意思啊，用QQ图可以检验分布形式是可以理解的，但是后面那句里面说不符合正态分布的进行内部转化然后提高正太性如何理解啊？