With another practice board exam behind me, I’m starting narrow in areas that I am consistently trip me up. While there are several areas that still need tuning up, there is one thing in particular that I decided I am just DONE mixing up:
SPECIFICITY vs SENSITIVITY
when considering the validity of a diagnostic test.
Consider this question:
Members of a health task force evaluate a proposal for a new adolescent screening program. The validity of the screening insturment is brought to question. Which measure of validity examines the instrument’s ability to identify diseased persons by comparing true positives?
- Adaptability
- Selectivity
- Sensitivity
- Specificity
What did you think? Did you say #3: Sensitivity? Lets break it down:
- Sensitivity: Is a measure of validity based on the probability that a screening test will be POSITIVE in someone with the disease or target condition (true positives).
- Specificity: Is a measure of validity based on the probability that a screening test will be NEGATIVE in someone who does NOT have the disease or target condition (true negatives)
So check this out:
A little way for me to remember…
You can also make your self a little table:
The top left representing SENSITIVITY (two Ts or positives)
The bottom right representing SPECIFICITY (two – or negatives)
Ok, so give this question a try. A little different approach:
If the forced expiratory volume in one second (FEV1) test is negative for airway obstruction in 99% of individuals without lung disease, the the measurement of FEV1 is:
- Sensitive
- Specific
- Reliable
- Valid
Did you recognize that the question is asking about TRUE NEGATIVES? That is right! The test has high SPECIFICITY (two – ) or #2 !
Go forth and concur those research questions friends!
A Cup A Day 