When might re-expressing data not be necessary?

Re-expressing data is typically used to stabilize variance or make relationships more linear, especially in cases where the original data does not meet the assumptions of linear regression or other statistical analyses. If the data already shows a linear relationship, there wouldn’t be a need to re-express it to achieve linearity because the linear model is already a good fit for the data.

Furthermore, if the variance in the data is stable across different levels of the independent variable, re-expressing the data to achieve homoscedasticity would not be necessary. Therefore, when both of these conditions are met—having a linear relationship and stable variance—there is no need to alter the data.

Hence, both scenarios presented justify the idea that re-expressing data is unnecessary, affirming the selection that both reasons are valid.