PT154 S1 Q19 ExplanationMedical researcher: At the Flegco

Answer choices, explained

1. A

   Correct75% picked this

   It compares the incidence of back injury between two groups who probably do not have the same risk

   Why this is right

   One group consists of people whose work involves lifting heavy objects. The other group consists of people whose work does not involve lifting heavy objects. Those two groups probably do not have the same risk factors for back injury. If non-lifters have a 10% chance of back injury, while lifters (without a belt) have a 50% chance of back injury, then putting back belts on these lifters might only bring their risk of back injury down to 20%. This situation would fit the evidence (belt wearers are more likely to get back injuries than the non-lifters), but it wouldn't fit the conclusion, because clearly back belts do help to prevent injuries if it lowered the lifters' risk from 50% to 20%.

   Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

   75%
2. B

   Not an Objection1% picked this

   It fails to address the possibility that Flegco Corporation employees are more likely to wear back belts than are employees who perform

   It doesn't hurt this argument at all to say that Flegco employees are more likely to wear back belts than are employees elsewhere. The author isn't claiming Flegco is representative in any way. She just looks at their employees, sees that the belt-wearing group gets more back injuries than the non-belt wearing group, and thinks that the belts apparently aren't helping them.

   1%
3. C

   Bad Conclusion Match13% picked this

   It takes for granted that if a factor is associated with an increased likelihood of a certain effect, that factor must

   When we see an answer structured like takes for granted that if X, Y then X should match the evidence, and Y should match the conclusion. Does the evidence discuss a factor associated with an increased likelihood of a certain effect? Yes, wearing a back belt is a factor associated with an increased likelihood of back injuries. Does the conclusion say that "back belts must causally contribute to back injuries"? Nope. It says back belts do not help prevent injuries, but it doesn't say that belts cause injuries.

   13%
4. D

   Bad Premise Match7% picked this

   It confuses the claim that a phenomenon does not causally contribute to a certain effect with the claim that that phenomenon causally

   When we see answers structured like confuses X with Y then one of them should be Evidence and the other should be Conclusion. The conclusion makes a claim that a phenomenon does not causally contribute to a certain effect: the phenomenon of wearing back belts does not causally contribute to injury-prevention. Does the evidence make a claim that that phenomenon causally contributes to preventing that effect? No, that would have sounded like "wearing back belts causally contributes to preventing injury-prevention". If this sounds like tortured language/logic, it is! Bail from this answer. It does not match. Preventing injury-prevention = making more vulnerable to injury. Just as we said with (C), the author is never saying that in evidence or conclusion that back belts cause more back injuries.

   7%
5. E

   Wrong Flaw4% picked this

   It fails to address the possibility that even if a factor is sufficient to produce a certain effect, its presence may not be necessary

   This describes the famous flaw of Necessary vs. Sufficient, in which the author presents a conditional rule and then applies that rule in an illegally backwards or opposite fashion to derive her conclusion. There was no conditional logic here, unless you count the "all" in the first sentence, "If you work at Flegco and your job involves lifting heavy objects, then you wear a back belt." If the author had committed the Necessary vs. Sufficient flaw with that rule, it would have sounded like "Melanie wears a back belt. Thus Melanie must work at Flegco, lifting heavy objects."

   4%