There is variability in the precision and accuracy of data. This is to be expected given the range of areas and the degree of documentation available. In many instances, the statistical information is considered to be accurate to within 5%. In most others, it is sufficiently accurate to rank as sound support for working estimates. For example, the Tropical Andes is believed to contain at least 20,000 known plant endemics, this being a rounded figure (many more species, probably thousands, remain to be discovered there). Another 14 such totals are rounded. The Cape Floristic Province, by contrast, is considered to contain exactly 5,682 known plant endemics; the same precision applies to another nine hotspots. Similar considerations apply to vertebrate data and to estimates of remaining primary vegetation.
This overall approach, uneven as it is, is justified for an analysis that seeks to convert a profound problem into a fine opportunity. After all, to decide that a potential hotspot should not be evaluated because it lacks a conventional degree of accurate data is effectively to decide that its conservation needs cannot be evaluated either, in which case its cause tends to go by default. Uncertainty can cut both ways.