21. DIAGNOSTIC ACCURACY OF A TEST Definition The extent to which the results of a diagnostic test reflect true disease status Terminology Accuracy / Validity interchangeable
87. Effect of prevalence on predictive value(Se=70%, Sp=90%) 93.0 50,000 Clinical suspicious prostatic nodule 5.6 500 Men, age 75or greater 0.4 35 General population PPV (%) Prevalence (case/100,000) Setting
88. Lead Time 1990 1997 2000 death Diagnosis and treatment Biologic onset of disease 1990 1994 2000 death Biologic onset of disease Screening: diagnosis & treatment
89. Length Bias 1995 2000 death Biologic onset of disease 1989 1994 death Biologic onset of disease Screening: diagnosis & treatment 2002 1994 Screening: