Carroll diagram
[Image:Carroll Diagram (simple).svg|thumb|A simple Carroll diagram.]
A Carroll diagram, Lewis Carroll's square, biliteral diagram or a two-way table is a diagram used for grouping things in a yes/no fashion. Numbers or objects are either categorised as 'x' or 'not x'. They are named after Lewis Carroll, the pseudonym of polymath Charles Lutwidge Dodgson.
Usage
[Image:Carroll Diagram (two criteria).svg|thumb|A more complex Carroll diagram.]Although Carroll diagrams can be as simple as the first one above, the most well known types are those similar to the second one, where two attributes are shown. The
Carroll diagrams are often learnt by schoolchildren, but they can also be used outside the field of education, since they are a tidy way of categorising and displaying information.