1.5.1 Using matrices
A matrix can be a useful way of organising your thinking about a topic. Suppose that you were asked: ‘How will you know when you have written a good assignment?’. Suppose as well that you thought ‘usefulness’ and ‘mark’ were the two measures by which you would judge an assignment. You could use a two-by-two matrix like the one shown in Figure 8.
The labels on the two axes of the matrix (the rows and the columns) are your two criteria, ‘usefulness’ and ‘mark’. Each of the criteria can be divided into ‘low’ and ‘high’ so that you now have four cells each of which describes a particular combination of ‘usefulness’ and ‘mark’. The four combinations represented by the matrix are: low usefulness/low mark, low usefulness/high mark, high usefulness/low mark and high usefulness/high mark. You would know that you had written a good assignment if it could be placed in the high usefulness/high mark cell of the matrix.
This two-by-two matrix describes the possibilities in a simple way (‘high/low’) and so enables you to think about them. The criteria (‘usefulness’ and ‘mark’) are the boundaries. Whenever you can confine the criteria (the boundaries) to just two, you can construct a two-dimensional matrix. You could also expand ‘high/low’ into three or more categories, or you could number your axes, for example from 1 to 9, if you wanted to create a larger matrix than the two-by-two matrix in the example.