Power transformations can often simplify the task of describing behavior in data that consist of positive measurements or counts. Tukey's diagnostic techniques based on two-dimensional plots are useful in searching for a suitable transformation in two types of data structures: multiple batches at different levels, and two-way tables. To these, we add plots for finding transformations in two other structures: a single batch, andyversusx.The basis for plots that indicate transformations for symmetrizing and for straightening is explored using second-order series approximations. For all four techniques, when the plot is roughly linear with slope 1 —p, the power of a transformation indicated by the plot isp.Each plot indicates whether any power transformation can be effective in achieving a desired objective.