Q13 - Five years ago, during the first North

[noah]

This has a tricky wrong answer! It's crucial to not pick the first nice answer that walks along and instead assume you've been fooled and look for a better one.

Here, the argument is concluding that the disease has become stronger. Why? Because a great percent of cattle who contract it now die, as compared to 5 years ago.

Since this is a weaken question, we're looking for any assumptions. The large one -- which is probably too large to show up in an answer choice -- is "Could the rise in the mortality rate be because of some other reason?" So what could be a specific reason? For one, there could be some physical explanation; for instance, perhaps the cattle that the disease is now affecting are weaker than the original ones who contracted the disease (perhaps it started in Texas Long Horn cattle and then moved to some flimsy breed raised in New Hampshire?). The other area for alternate explanations that should come to mind is that the numbers might be somehow wrong. Whenever the LSAT brings up percents, be on the look-out for whether the totals have been somehow tampered with. This takes different forms (which is too large a discussion for here). In this case, one way to disrupt the argument is to suggest that the number of cattle that now gets the disease is actually larger than is reported, then that X number of cattle dying, which we thought was 18%, is actually a much smaller percentage. Or, it could be that the previous percent reported was much lower than what it actually was.

To put some numbers behind this:

2005: 100 cows contract disease, all are reported and 5 die. 5% actual and reported mortality.
2010: 500 cows contract disease, BUT only 100 reported, and 20 die. 4% mortality, but it looks like it's 20%!

(D) takes advantage of this possible number play. Farmers have figured out how to treat the mild cases and no longer report those to authorities, so the total number of affected cows is actually much larger than is reported. But, they still may be reporting the deaths, meaning that the reports indicate a higher percentage of death-causing cases than is actually true.

(A) is incorrect because it has the opposite effect of (D) -- it raises the number of cattle that were recently killed by the disease, which strengthens the conclusion that the disease has become more virulent.
(B) suggests the disease was not as strong as originally thought, perhaps strengthening the conclusion.
(C) is irrelevant. What does the inoculation program have to do with whether the disease and whether it's become stronger?
(E) is similarly irrelevant. It does not weaken the idea that the disease has become stronger.

You might want to try and figure out a different answer choice that would have taken advantage of the same sort of weakness but focused on the original mortality rate. Feel free to post it and we'll check your thinking.

[mchuynh]

I still don't get why the answer is D. I eliminated everything and was stuck with B and D. I eliminated D because I didn't think that would weaken the argument.

5 years ago Death rate was 5 percent

Today it's 18 percent
conclusion- cxc has increased in virulence..

After reading the stimulus, I was trying to find a alternative cause... since this one seems like a cause /effect type of question

I couldn't really find one so I started to eliminate the choices. Would D strengthen the stimulus instead? since farmers are treating mild cases- which means that it should be lower, but it's not it's 18%? so wouldn't that strengthen the conclusion that CXC has increased?

Is there something wrong with my reasoning for weakening questions?

[noah]

You're missing a key detail. What specific percent is the argument discussing? It's not the percent of cows that contract the disease...

Figured it out?

It's the percent of cows that DIE from the disease.

[nflamel69]

is the key detail is reported cases? because all the percentage is based on the statistic we know, so it could be that the virus hasn't gotten more deadly, but since the weaker ones are cured, the ones we know are the deadly ones. I got this question wrong, but hopefully I got the reasoning correct this time.

[noah]

is the key detail is reported cases? because all the percentage is based on the statistic we know, so it could be that the virus hasn't gotten more deadly, but since the weaker ones are cured, the ones we know are the deadly ones. I got this question wrong, but hopefully I got the reasoning correct this time.

Exactly! Keep an eye on "reported" vs. "actual" - that switch shows up from time to time.

[magnusgan]

Reported got me too. Dang!

[WaltGrace1983]

Just wanted to add that even if one missed the "reporting" detail (like I probably did the first time I did this question awhile back), the two most tempting answers actually would probably strengthen the argument.

There are two reported statistics: (five years ago) and (today)

(A) says that, (today), 18% is actually too low! Why? Because CXC has actually killed more cows than have been attributed to it. The argument thought it was only 18% but it actually seems that, because CXC has killed more cows than we reported, >18% have been killed.

(B) focuses on (five years ago) and says the opposite. It says that 5% is too high! Why? Because we accidentally attributed some deaths to CXC that were NOT actually caused by CXC. Thus, the 5% number is inflated.

These both strengthen the argument by actually widening the gap between 5% and 18%. (D) would actually narrow the gap, even ever so slightly, by showing that the "reported" number in the (today) statistic is actually bigger than the "reported" number in the (five years ago) statistic. If that is the case, 18% should really be lower.

My point is that even if you DID miss this crucial detail and picked (A) or (B) because, let's face it, they do sound very LSAT-y, this would still be some less-than-perfect reasoning.

(E) may even strengthen a bit too but only with some BIG assumptions and (C) is just out of scope.

[zen]

I'll explain why (D) is the correct answer.

The death rate from the disease on all reported cases of the disease used to be 5 % but is now 18%.

Since this is a weaken question, we need to be on the lookout for alternate explanations. Finding an alternate explanation weakens the argument by showing that the author's conclusion need not be correct i.e. there could be other possibilities.

Answer choice (D) provides this alternate explanation. What it is basically saying is that farmers are now reporting less cases; before they would report ALL cases, now they are only reporting the more serious cases they cannot treat themselves( the cases that would more likely involve fatalities!).

Since they are now only reporting the more serious cases that I'd assume are more correlated with fatalities, it makes sense that the number of reported cases involving fatalities would go up because less cases are being reported that wouldn't presumably involve fatalities (the more mild cases). Therefore, contrary to the author's argument, CXC hasn't become more virulent (I just read this as "deadly" in my head), its just only seems that way due to what instances of the disease are being reported.

I hope that helps!