Trace element analysis in environmental and occupational health: box plot representation of elemental composition...

Box plots are used in the visual representation of large data sets and in exploratory data analysis. They display batches of data with five values being used to describe the data set. These are the median, the upper and lower extremes of the range of values and the 75 and 25 percentiles. A notch about the median, e.g. at the 95 percent level of significance, can be incorporated in the display allowing the difference between the medians of different sets to be established. The method, although not recently established, has so far found little application in the analytical field. Hence, in an effort to strengthen its applicability, the features and capabilities of box plots, in terms of data reporting and insight into the data set, are here described through elemental composition studies in relation to environmental and occupational health.