The various assays can be conveniently divided into two main divisions, some assays are quantitative in that they produce precise result. Many of these assays are automated and can be related to international standards. Qualitative assays are less specific and will give answers such as normal-abnormal, or positive-negative results. The problem is that interpretation of results may be subjective and require special expertise in carrying out the test. Many research tests are in this category at first, and many become quantitative assays when more fully developed.