Psychological comments -- for the puzzled
-----------------------------------------

The main motive for transformation is greater ease of description.
Although transformed scales may seem less natural, this is largely a
psychological objection. Greater experience with transformation tends to
reduce this feeling, simply because transformation so often works so
well. In fact, many familiar measured scales are really transformed
scales: decibels, pH and the Richter scale of earthquake magnitude are
all logarithmic.

Often it helps to transform results back again, using the reverse or
^inverse^ transformation:

    reciprocal             also reciprocal

    t = 1 / x              x = 1 / t

    logarithm base 10      10 to the power

                                 x
    t = log  x             t = 10
           10

    logarithm base e       e to the power

                                x
    t = log x = ln x       t = e
           e

    logarithm base 2       2 to the power

                                x
    t = log x              t = 2
           2

    cube root              cube

         1/3                    3
    t = x                  x = t

    square root            square

         1/2                    2
    t = x                  x = t


Also see:
---------

Reasons for using transformations                         help @trreason@

Review of most common transformations                     help @trreview@

Transformations for proportions and percents              help @trpropor@

How to do transformations in Stata                        help @trstata@