Did the diagnostic test results influence the decision to perform the reference standard?
The gold standard is by definition more expensive or more invasive, so there is a natural reluctance to apply the reference standard. The ideal research study would require every patient to endure both the diagnostic test and the gold standard, but sometimes this is difficult. Suppose the gold standard involves surgery. What do you tell the patients who test negative on the diagnostic test (we suspect that everything is okay, but we want you to submit to this surgery to preserve the credibility of our research findings). Are the results for the diagnostic test clinically significant? A diagnostic test is clinically significant if knowledge of the results of the diagnostic test can substantially alter your belief about whether your patient has a particular disease. The likelihood ratio will help you answer this question. A likelihood ratio for a positive result smaller than 2 or a likelihood ratio for a negative result larger than 0.5 is pretty much worthless. Can you extrapolate the re
