The logarithmic (log) transformation is a simple yet controversial step in the analysis of positive continuous
data measured on an interval scale. Situations where a log transformation is indicated will be reviewed. This
paper contends that the log transformation should not be classed with other transformations as it has
particular advantages. Problems with using the data themselves to decide whether or not to transform will
be discussed. It is recommended that log transformed analyses should frequently be preferred to untransformed
analyses and that careful consideration should be given to use of a log transformation at the protocol
design stage.