<unk> es are tests performed on blood plasma of patients or test subjects to distinguish factor deficiencies from factor inhibitors, such as lupus anticoagulant, or specific factor inhibitors, such as antibodies directed against factor VIII. The basic purpose of these tests is to determine the cause of prolongation of Prothrombin Time (PT), Partial Thromboplastin Time, or sometimes of thrombin time (TT).<unk> es take advantage of the fact that factor levels that are 50 percent of normal should give a normal Prothrombin time (PT) or Partial thromboplastin time (PTT) result. Factor deficient plasmas (Adsorbed Plasma & Aged Plasma, etc.) are used in<unk> es. Plasma with known factor deficiencies are commercially available but are very expensive, so they are often prepared in the laboratory and can then be used for<unk>  experiments.
Mixing study
Platform trial
Subgroup analysis
Agent study
Intersalt study
Parallel study
Bioprospecting
Causal graph