Reagent Kits, DiagnosticImmunoassayOccult BloodHematologic TestsIndicators and ReagentsSensitivity and SpecificityGuaiacColonoscopyImmunoenzyme TechniquesMass ScreeningSigmoidoscopyColorectal NeoplasmsFluorescence Polarization ImmunoassayDiagnostic Tests, RoutineEnzyme Multiplied Immunoassay TechniqueEarly Detection of CancerDiagnostic ErrorsEnzyme-Linked Immunosorbent AssayPredictive Value of TestsSulfhydryl ReagentsReproducibility of ResultsFalse Positive Reactions