Честотите се определят като много чести (> 1/ 10); чести (> 1/ 100, < 1/ 10); нечести (> 1/ 1 000, < 1/ 100); редки (> 1/ 10 000 и < 1/ 1 000); много редки (< 1/ 10 000).
Frequencies are defined as very common (> 1/ 10), common (> 1/ 100 ,< 1/10), uncommon (> 1/ 1,000 ,< 1/100), rare (> 1/ 10,000, < 1/ 1,000), very rare (< 1/ 10,000).