SinaPlot: an enhanced chart for simple and truthful representation of single observations over multiple classes

Abstract Recent developments in data driven science, in particular computational biology, have led scientists to integrate data from several sources, over diverse experimental procedures, or databases. This alone poses a major challenge in truthfully visualising data, especially when the amount of data points varies between classes. To aid the presentation of datasets with differing sample size we have developed a new type of plot overcoming limitations of current standard visualization charts. Plots like bar charts, violin plots, strip charts or boxand-whiskers plots may provide visual information about mean/median, variance of the data, number of data points or density distribution of data; still, only a combination of these plots may provide all relevant information. We have designed a new and simple plot inspired by the strip chart and the violin plot that operates by letting the normalized density of points restrict the jitter along the x-axis. Τhe plot displays the same contour as a violin plot, but resembles a simple strip chart for small number of data points. In this way the plot conveys information of both the number of data points, the density distribution, outliers and data spread in a very simple, comprehensible and condensed format. The package for producing the plots is available for R through the CRAN network (https://cran.r-project.org/web/packages/sinaplot/index.html). In order to aid users without experience in R we also provide access to a web-server accepting excel sheets to produce the plots (http://servers.binf.ku.dk:8890/sinaplot/) .