The body of anyone infected by virus X will, after a week, produce antibodies to fight the virus; the antibodies will increase in number for the next year or so. █████ ██ ███ █ ████ ████ ████████ █████████ ███ ████ ██████████ ███ ███████ ██ █ ██████████ █████ ██ █████████ ████ ████ ███ ██ ████ ██████ ███ █████ ████ ██ █████████ ██ ████████ ██ ██████ █ █████ ███ ████ ████ ██████ ███ ███ ███ ██████
In most strongly supported questions, we can just treat the stimulus as a big ol' list of rules – 10 commandments style – any one of which could hold the key to the correct answer. Here's a list of the stimulus' claims, with one claim in particular broken out with the benefit of hindsight:
- The body of anyone infected by virus X will not produce antibodies for a week
- After a week, the body of anyone infected by virus X will produce antibodies
- Antibodies will increase for about a year
- We can test for antibodies – whether they're present, and how many are present
- If antibodies are detected, we can estimate how long someone has had the virus within the first year of infection
It's probably doable to catch that "after a week" nuance up front and anticipate that it'll feature prominently in a right or wrong answer choice. I say that because it's atypical – it nestles one claim inside another in a way that isn't super common.
I personally didn't catch this one up front, though, and it's not really a big deal if you didn't either as long as you're adept at the process of elimination. Run once through the answers noting promising contenders and eliminating any clearly-wrong choices, then cross-reference the remaining answer choices against the stimulus.
Which one of the following ███████████ ██ ████ █████████ ██ ███ ██████████ ██████
Antibodies increase in ██████ ████ █████ ████ ████ ████████ ███ ██████
We do know antibodies increase for a year or so, but we don't know why they stop increasing after about a year, or when they manage to defeat the virus. Perhaps they defeat the virus within a few weeks but continue to produce antibodies as a prophylactic against future infection.
Without the test ███ ███████████ █████ ██ ██ ███ ██ ████████████ ███████ █ ██████ ███ █████ ██
We can view the flaw here as a confusion of sufficiency and necessity. We know the antibodies test is one way to detect the virus, but nothing in the stimulus indicates it's the only way.
Antibodies are produced ████ ███ █████ ██████████ ████ ██████ ██ ██████ ██ ███ █████ ████ █████████
The stimulus makes no mention of any limitations on antibody production. It gives us one scenario in which the body produces antibodies, but never says antibodies are only produced [in any given circumstance].
If a person ███████ ████████ ██ █████ █ █████████████ █████ ██ ██ █████ ██ ███ ██████ ██ ██████████ ████ ███ ██ ███████ ██ ███ ██████████ █████
The most reasonable reading of the stimulus' first sentence is that it describes what happens upon an initial infection: after a week, antibodies are produced and increase in number for about a year.
Perhaps you read the stimulus to mean "the body of anyone who has virus X in their system…" Grammatically, that reading is allowable. It's not a reasonable reading, though, because the "after a week" piece doesn't make sense if we're talking about someone who has had the virus for a long time.
(D) would be more promising if it told a story of infection, disinfection, and reinfection. Perhaps with additional info about how antibodies stay around even if someone is briefly disinfected.
Anyone infected by █████ █ ████ ███ █ ████ ████ ██ ███████ █████████ ██ ██████ ██ ███ ████████ █████
Answer five questions and we'll estimate your score.
It takes about five minutes.
Take the free diagnostic