Basic transformation method of index data
| Transformation method | Logarithmic transformation | Square transformation | Reciprocal transformation | Square root transformation |
|---|---|---|---|---|
| Type of data | Equal ratio data or the ratio of each group of values to the mean is not much different | The variance is inversely proportional to the mean squared or left skewed | The variance is proportional to the mean squared and does not tend to or less than zero | Poisson distributed or slightly skewed, or the sample variance is positively related to the mean |
| Transformation method | Logarithmic transformation | Square transformation | Reciprocal transformation | Square root transformation |
|---|---|---|---|---|
| Type of data | Equal ratio data or the ratio of each group of values to the mean is not much different | The variance is inversely proportional to the mean squared or left skewed | The variance is proportional to the mean squared and does not tend to or less than zero | Poisson distributed or slightly skewed, or the sample variance is positively related to the mean |