Statistics notes: Transformations, means, and confidence intervals
- 27 April 1996
- Vol. 312 (7038) , 1079
- https://doi.org/10.1136/bmj.312.7038.1079
Abstract
When we use transformed data in analyses,1 this affects the final estimates that we obtain. Figure 1 shows some serum triglyceride measurements, which have a skewed distribution. A logarithmic transformation is often useful for data which have positive skewness like this, and here the approximation to a normal distribution is greatly improved. For the untransformed data the mean is 0.51 mmol/l and the standard deviation 0.22 mmol/l. The mean of the log10 transformed data is -0.33 and the standard deviation is 0.17. If we take the mean on the transformed scale and back transform by taking the antilog, we get …Keywords
This publication has 1 reference indexed in Scilit:
- Statistics Notes: LogarithmsBMJ, 1996