You have clinically diagnosed a patient as having SLE and ordered 6 tests, out of which 4 have come positive and 2 have negative. To know the probability of SLE at this point, you need to know:
To know the probability of SLE at this point,We need to know Prior probability (Prevalence) of each test, sensitivity and specificity of each test Probability of having a Disease means PPV i.e. Positive Predictive Value and it depends upon (BAYES'THEORM) sensitivity specificity and disease Prevalence
Incidence of SLE and predictive value of each test
Incidence and prevalence of SLE
Relative risk of SLE in this patient
Prior probability of each test, sensitivity and specificity of each test
Biostats