There has been considerable controversy in recent years concerning whether the effects of competition can be seen in records of species occurrences on islands. Questions concern whether when species A is present on an island, species B tends to be absent or, alternatively, whether species A and B tend to occur together. The data to be considered can be represented by an array of zeros and ones, of the form shown in Table 14.1. This example is too small for a meaningful test, but it does allow the discussion of what are the important

considerations with data of this type. Such an array of zeros and ones will be referred to as an occurrence matrix.