A box and whisker plot is a graphical method of displaying variation in a set of data. In most cases a histogram provides a sufficient display; however, a box and whisker plot can provide additional detail while allowing multiple sets of data to be displayed in the same graph. Some types are called box and whisker plots with outliers.
Can you compost Leylandii branches and hedge clippings - Yes. We were quite surprised to learn some experienced composters advise not to add Leyandii cuttings as they are apparently too acidic. Composting bacteria can remain active in all but the most acidic conditions.
Depends on what kind of charcoal. If it is the type that has additives including lighter fluid, then I wouldn't use it in compost (I do spread it on top of my flower beds, they don't seem to mind. But if it's pure charcoal (which is just burnt wood) then you can use it.