Hi Victoria,
First, great work putting in the hours now and staying ahead of things, you’re going to do GREAT in the Spring!
Second, thank you for catching this error. However, the correct answer should be B, not C or D.
Let’s dive into this. A sensitivity of 98% means that the test will correctly identify 98% of people truly at high fall risk, but it will fail to identify 2% who are truly at fall risk.
A specificity of 21.2% means that the test will correctly identify 21.2% of people not at fall risk, but will also identify 78.8% as having fall risk when they do not
In other words, the chance of a false positive is very high with the test in option C.
The answer should be “B”. Your sensitivity is still very high, and the specificity is also pretty high. Because the specificity is high, there is less chance of a “false alarm”. In other words, if a person does screen positive, it is more likely they are actually positive and not a false positive.
Here is another way to look at it: Option b (Sn 97.5%, Sp 81.9%) provides the highest chance of obtaining a true positive because it combines very high sensitivity with moderate specificity. Sensitivity reflects the test’s ability to correctly identify individuals who have the condition — so a high sensitivity means most true cases will be detected. While specificity helps reduce false positives, the relatively high specificity in this option ensures that the number of false positives remains reasonably low. Together, these values increase the Positive Predictive Value (PPV), meaning a positive test result is more likely to be a true positive.
Hope this helps!
Jonathan