Current standards of data presentation and analysis in biological journals often fall short of ideal. This is the first of a planned series of short articles, to be published in a number of journals, aiming to highlight the principles of clear data presentation and appropriate statistical analysis. This article considers the methods used to show data, in particular the value of the dot plot, and methods to summarise the distribution of values. The uses of measures such as standard deviation, standard error of the mean, and confidence intervals are contrasted. (Contains 3 figures.)