Editing Assay (section)

===Result type===
Depending on the quality of the result produced, assays may be classified into:
# '''Qualitative assays''', i.e. assays which generally give just a pass or fail, or positive or negative or some such sort of only small number of qualitative gradation rather than an exact quantity.
#'''Semi-quantitative assays''', i.e. assays that give the read-out in an approximate fashion rather than an exact number for the quantity of the substance. Generally they have a few more gradations than just two outcomes, positive or negative, e.g. scoring on a scale of 1+ to 4+ as used for blood grouping tests based on RBC [[Agglutination (biology)|agglutination]] in response to grouping reagents (antibody against blood group antigens).
# '''Quantitative assays''', i.e. assays that give accurate and exact numeric quantitative measure of the amount of a substance in a sample. An example of such an assay used in coagulation testing laboratories for the most common inherited bleeding disease - [[Von Willebrand disease]] is [[Von Willebrand Factor|VWF]] antigen assay where the amount of VWF present in a blood sample is measured by an immunoassay.
# '''Functional assays''', i.e. an assay that tries to quantify functioning of an active substance rather than just its quantity. The functional counterpart of the VWF antigen assay is [[Ristocetin]] Cofactor assay, which measures the functional activity of the VWF present in a patient's plasma by adding exogenous [[Formaldehyde#Tissue fixative and embalming agent|formalin-fixed]] [[platelet]]s and gradually increasing quantities of drug named ristocetin while measuring agglutination of the fixed platelets. A similar assay but used for a different purpose is called [[Ristocetin Induced Platelet Aggregation]] or RIPA, which tests response of endogenous live platelets from a patient in response to Ristocetin (exogenous) & VWF (usually endogenous).