Psychology MCAT Practice Exam

What does a steeper ROC curve indicate in terms of a diagnostic test?

1. A higher false alarm rate

2. A more accurate test

3. A greater disparity in sensitivity

4. A decrease in overall effectiveness

The correct answer is: A more accurate test

A steeper ROC (Receiver Operating Characteristic) curve indeed indicates a more accurate test. The ROC curve is a graphical representation used to assess the performance of a diagnostic test by plotting the true positive rate (sensitivity) against the false positive rate (1-specificity) at various threshold settings. When the ROC curve is steeper, it means that for a relatively small increase in the false positive rate, there's a significant increase in the true positive rate. This implies that the test is effectively distinguishing between the positive and negative cases, demonstrating higher sensitivity. Essentially, a test that produces a steeper ROC curve can identify true positives with fewer false alarms, suggesting overall improved accuracy in diagnosing the condition in question. The other concepts, while relevant in assessing diagnostic tests, do not accurately describe the implications of a steeper ROC curve. For instance, a higher false alarm rate would reflect insufficient discrimination between classes, which is contrary to what a steep curve indicates. Likewise, greater disparities in sensitivity would not necessarily correlate with the steepness of the ROC. A decrease in overall effectiveness suggests a lower area under the curve (AUC), which is not reflected by a steeper ROC curve, as that would typically indicate better effectiveness.