Figure 2

Change in headache days pre- and post-BOTOX in chronic migraine sufferers*. *In this box plot, the middle line is the median. The ‘box’ part represents the inter-quartile range (IQR), i.e. the middle half of the data. The ‘whiskers’ (i.e. the lines that come out from the box) then typically represent the minimum to maximum points. The exception is for points that are more than 1.5 times the IQR away from the box, in which case these are plotted separately. The value of 1.5 IQRs is chosen by convention in statistics.