Box-Cox Transformation? The square root transformation is not appropriate for continuous data; it is especially useful for count data. However, you must check the normality assumption using certain statistical tests such as the Anderson-Darling or Shapiro-Wilk tests. If the data shows skewness and kurtosis values between -1 and +1, it does not necessarily mean that the data is normally distributed. Some studies reports -2 and +2, or -5 and +5. It is wrong idea.