#3 - A certain strain of bacteria was found in the stomachs

[Administrator]

Complete Question Explanation

Strengthen-CE. The correct answer choice is (E)

In this stimulus the author draws a causal conclusion based on anecdotal evidence. One researcher ingested a bacteria and later developed an ulcer. The author concludes that "it is highly likely that the bacteria strain induces ulcers." In order to strengthen this argument we must find the answer choice that either bolsters the causal claim directly, or rules out alternative explanations for the observed effect.

Answer choice (A): Since the author makes no claims whatsoever about kidney disease, this answer choice is completely irrelevant to the question of whether the bacteria induces ulcers.

Answer choice (B): The lack of other effects plays no role in the assessment of whether the researcher got the ulcer as a result of the bacteria, so this answer choice is incorrect.

Answer choice (C): If the bacterial strain has not been showed to induce ulcers in other animals, then it seems less likely that it does so in humans. Although this evidence is certainly no conclusive, it does weaken the author's argument to some extent.

Answer choice (D): The expertise of the researcher is irrelevant to the question of what caused that researcher's ulcer, so this answer choice is incorrect.

Answer choice (E): This is the correct answer choice. A large sample of people who did not have ulcers also did not have the referenced bacteria strain. This shows many examples where the cause is absent, and the effect is absent. This lends support to the causal argument in the stimulus.

[lunsandy]

Hi Powerscore,

Can someone explain answer B further? I was deciding between B and E and ended up choosing B because I thought that if the researcher did not develop any other serious health problems within a year besides ulcer then it would strengthen the cause that the bacteria strain induces ulcers only. So I saw B as a defender of other possible factors.

Thanks a lot!

[Jennifer Janowsky]

Can someone explain answer B further? I was deciding between B and E and ended up choosing B because I thought that if the researcher did not develop any other serious health problems within a year besides ulcer then it would strengthen the cause that the bacteria strain induces ulcers only. So I saw B as a defender of other possible factors.

Great question!

Although (B) is an attractive answer, whether or not the bacteria caused only ulcers and not other ailments was not very important to the conclusion. For example, if it was found that the bacteria caused both ulcers and a fever, that would not change the conclusion that "the bacteria strain induces ulcers."

The conclusion states that if you have the bacteria, that means you will have ulcers. However, if (E) is true and thousands of people without ulcers also lack this bacteria, this strengthens a conditional idea: that if you do not have ulcers, you will not have the bacteria.

I hope this answers your questions!

[lunsandy]

Hi Jennifer!

Thanks for the quick reply and your answer. The fact that other symptoms may or may not appear alongside with the bacteria strand does nothing to our argument - our focus is to strengthen that bacteria strand CAUSES ulcer. Thanks for your help!

[Jennifer Janowsky]

lunsandy--

My pleasure! Glad I could help!

[Jlms]

Hi,

I got this one right, but relied on process of elimination and kept on going back and forth on it before finally moving on. My concern was that this was taken a lack of evidence against as evidence for, which I didn't think could strengthen the argument.

Thanks for any clarification you can provide. Test is 10 days away eeeek

[James Finch]

Hi JLMS,

This is a classic causal stimulus, where the argument is trying to prove that one thing is causing another thing. These tend to be associated with Strengthen and Weaken questions, although other question types like Flaw or Assumption could be present as well. Whenever you see a causal stimulus like this, you always want to be thinking about assumptions being made and how to strengthen or weaken the argument based on making the assumption true or false. With a causal Strengthen question, we're going to need to either eliminate an alternate cause, show the cause and effect together in a different setting, show the absence of the cause and the absence of the effect in a different setting, or in very rare instances, eliminate the possibility of reverse causation.

With this stimulus, my first thought was towards eliminating a potential alternate cause for the ulcers, or perhaps showing another study that bolster the causal connection. However, what we end up getting in (E) is another instance where we don't have the cause (bacteria) and we don't have the effect (ulcers). This also serves to strengthen that causal connection, making it the correct answer choice.

Hope this helps, and good luck on your exam!

[jennifersuh]

Hi!
I got this right but wasn't confident in the answer choice. To me, E does seem to strengthen the stimulus, but only by a little bit. Is that a correct observation?
I know that even if it only strengthens it a little, it still works.

[Robert Carroll]

Jennifer,

Answer choice (E) is an example of helping a causal argument by showing that when the cause is absent, the effect is also absent. That's a typical way to strengthen causal arguments. And yes, that might only strengthen a little, but it has a definite positive effect, so it's correct.

Robert Carroll

[dorritanqizhao]

HI!

What if other diseases might cause the ulcer? In that case, the absence of any other disease can serve to eliminate alternative causes. Can anyone help me with this explanation?