Last year, after the number of subway riders who had had their pockets

Question

Last year, after the number of subway riders who had had their pockets picked at Central Station had risen to an all-time high, the transit authority erected signs in Central Station telling riders to beware of pickpockets. In the year since the signs have been erected, though, riders have had their pockets picked at Central Station at a per-capita rate nearly double that before the signs were erected.
 
Which of the following, if true, helps to explain the discrepancy pointed out in the passage?
 
(A) Since Central Station’s major renovation, during which the signs were erected, Central Station has become much more attractive to tourists from out of town.

(B) Rising gas prices and a surging downtown job market have caused the daily number of riders at Central Station nearly to double within the past year.

(C) Riders walking past the new signs tend to rummage through their pockets or feel through their clothes to verify the presence of their possessions.

(D) The number of individuals convicted of petty theft or grand theft for picking pockets at Central Station has decreased within the past year.

(E) Most of the pickpockets’ victims were riding the subway during peak travel hours, when Central Station is especially crowded.

b]My reasoning: 
Pick-pocketing was at an alltime-high. Signs tell people now to be aware of pickpocketers. However, the per-capita-rate of pick-pocketing has doubled.

B.) Does explain that the number of pick-pocketing incidents has increased. However, the question asks for the per-capita-rate, therefore INCORRECT.
C.) If you assumed that potential thiefs would see where people have their belongings this could be an explanation to the paradoxon. However, I could not assume this right away, as it is not mentioned. Therefore, INCORRECT.
D.) A decreasing number of convictions has nothing to do with an increasing per-capita-rate of pick-pocketing. Either out of scope or the answer would need to contribute more explanations to qualify as an answer. Further, this does not explain the paradoxon that is mentioned by the sign. INCORRECT.
E.) There is no indication why the signs should have any influence on this. INCORRECT.

Therefore A.) should be correct. There are more people that are especially unaware of their stuff. Therefore the per-capita-rate should increase.

MGMAT says to A.): 
The riders’ city of origin is irrelevant to the frequency of pickpocketing, unless unwarranted assumptions are made about the vulnerability of out-of-towners to pickpocketing. ("However, we do make assumptions about C.)???")

to C.):
If riders walking past the new signs tend to rummage through their pockets or feel through their clothes to verify the presence of their possessions, then lurking pickpockets will be able to locate those possessions by watching the riders’ hands – something which will help them to steal the possessions, and which they were unable to do before the new signs were erected.

IanStewart · Accepted Answer

I don't think this is a good question at all; I can justify almost all of the answer choices by making appropriate assumptions, yet can justify none of them without making assumptions.

Something must have changed since the signs were erected for the pickpocketing rate to have changed, so we're looking for an answer which describes a potentially relevant change. If "Central Station has become much more attractive to tourists from out of town" (where else would tourists be from?) then the population of potential victims has changed; it's certainly reasonable to think that the pickpocketing rate might therefore change. Answer A seems like a fine answer to me. This has nothing to do with 'common stereotypes' and all to do with population bias; if you do an experiment on one population, you can reasonably expect different results if you do the same experiment on a different population. I'd add that you also can't use the criterion "be suspicious of common stereotypes" to rule out answer choices on the real GMAT, since the real GMAT will never include even the vaguest allusion to any kind of stereotype.

Answer B also describes a change since the signs were posted. It's certainly not far-fetched to think that pickpockets can operate more easily in a crowded environment, so B seems like a justifiable answer.

Answer C suggests that the signs are actually working; passengers are more vigilant about their possessions because of the warnings. The justification for answer C in the OE is, to be generous, tenuous, and is based on just as many assumptions as would be a justification for the other plausible answers.

I'm not sure why no one has considered D here. If fewer pickpockets are being prosecuted/convicted, then it's reasonable to think there will be fewer pickpockets in jail and more pickpockets in Central Station, and further there will be less of a deterrent to pickpocketing if there is less reason to fear conviction. It seems like a possible explanation for the increase in pickpocketing incidents.

E is the only answer that I think can be discarded out of hand, since it doesn't describe anything that has necessarily changed since the introduction of the signs.

I suppose the OE rules out B and D because they don't relate the posting of the signs to the increase in pickpocketing incidents, but it's not clear from the language of the question that we need to do that; any alternate explanation is enough to explain the 'discrepancy', whether that explanation relates to the signs or not.

parker · Answer

Hey guys,

I agree that you have to make some assumptions about C--something that might help with this one is knowing that you *almost always* have to make some assumptions (unless you are in one of those rare, lsat-like questions with more formal logic). It's more accurate to think of the real question here as what " most  explains" the discrepancy...meaning--which of the choices requires the  fewest and smallest  assumptions? It's all relative.

The discrepancy that we're trying to address is  "why did the per capita instances of pickpocketing double after warning signs were posted?"

I won't go into all the choices, since the original poster copied the explanation. The main contention in this thread seems to be between A-B-C, so let's assume we got rid of D and E and deal with these.

As a couple of posters mentioned above, * per capita * is a huge red flag phrase here. That means the number of pickpocketed people divided by the total number of people, doubled. This could happen a number of ways, so let's use a number to help make the situation tangible--100 people, and 10 are pickpocketed per day, so there's an original per capita pickpocket rate of  0.1 .

(1) if the total population stays the same--100 people, but the rate doubles to 0.2, or 20 people, that means that out of a (fictionalized) 100 people, 10 of the people who were NOT pickpocketed before ARE pickpocketed now.

(2) if the total population increased--let's say, it increased by 100%, so we now have  200  people. In order for the rate to double to 0.2, we would need 20% of the new total population (200 people), or  40  people, to be pickpocketed after the signs go up. Notice you had to increase the number of pickpocketed people by more than two, to compensate for the ratio increase AND population increase.

(3) if the total population decreased--let's say, to 50 people. The per capita pickpocket rate we're aiming for is 0.2, and 20% of 50 is 10, so 10 people still get pickpocketed, but there are only 50 people total, so the only people who left the original population were non-pickpocketed people.

Choice (A) says that the station has become much more attractive to tourists since the signs were posted during a recent renovation. Now in general, it's a good idea to be  suspicious  of assumptions that fall into  common stereotypes ; the test-writers know many common "real world" broad assumptions, and will use that to trap people. There is a broad stereotype about tourists being easy targets. But even if that were true (assumption 1) AND tourists are TWICE as likely to get pickpocketed (assumption 2) we'd have to make another assumption (no.3) about the rest of the population balancing out in a way to result in our desired statistic. That's the long version--the short version is that COMMON STEREOTYPES THAT ARE NOT SPECIFICALLY JUSTIFIED IN THE ARGUMENT should be targets of  major suspicion  as you go through choices. There isn't a necessary causal link between being a tourist and being an easy target--I, for one, am super paranoid and careful when I travel and have never (knock on wood) been pickpocketed while traveling, though I have in my home city!

Choice (B) doesn't necessarily help us because the phase " per capita " is in the argument. Look at situation #2 above-- if the traffic doubles, but the rate of pickpocketing is the same, the per capita rate doesn't change. In our example above with the population of 100 and a 100% increase in population, the rate of pickpocketing would have to quadruple to give us a doubled per capita rate.

Choice (C) does involve some assumptions,yes-- that the pickpocketers will pay attention to the rummaging going on and use it to their advantage. But this is not a terribly illogical assumption to make, since their goal is to pickpocket people, and these people are behaving in an obvious way that would assist that goal.

Hope this helps. Remember that correct/incorrect on verbal can seem relative, which is why you should ALWAYS go through all the answers and eliminate what's definitely wrong (or has the most problems) rather than trying to find the perfect answer.

nsvikin · Answer

I go for A

C is making too many assumptions.

Gottesschaf · Answer

Maybe the answer wants to explain why these specific riders experienced a higher rate of pick-pocketing? Then it would not explained clearly enough in the question imo.

carcass · Answer

for me is clear.

in A nothing mentioned the fact that the central station was renewed

c instead has good reasons to be the answer........

ajit257 · Answer

I am not convinced either. C makes far too many assumptions.

arbinose · Answer

One can assume that tourist can be easy target for pick pocketing, yet it is difficult to find a correlation as even tourist can read the beware board and become cautious about their possessions, so A can be easily rule out, C seems like the only somewhat logical explanation for the given discrepancy.

gmatpapa · Answer

I agree that C is making too deep assumptions.

I feel B is the right answer. Double the the traffic, double the pick pocketing.

gmat1220 · Answer

Actually the rate is going to go down with the increase in the number of people. Since we talking about per capita rate. B is going to aggravate the discrepancy.

gmatpapa · Answer

Or we can look at it this way- more the number of riders, more the opportunities for pick-pocketers. Hence, as the number of riders doubles, so does the number of instances of pick pocketing. This is what is also implied in the fact set.

naveenhv · Answer

I went for B because, since the no of people increased, the no of pick pockets also increased and hence the rise in per ca pita. But A is also a close contender.

arbinose · Answer

Per capita increase manifest that even those commuters became the target of pickpockets who were not been picked by the pickpockets in previous occasions, now the question is why so?
There must be something motivating the pickpockets to rob them, but what?
Perhaps when commuters look for their valuables; pickpockets will be getting the clues about their potential target.

gmatpapa · Answer

I believe you are vouching for C. If the reasoning in C is to be believed, you also have to make an assumption that the pick-pocketers are actually standing near the signs and keeping a constant eye on people who are nearing the signs. Do we have anything in the passage which leads us to substantiate this assumption? I guess not.

So, IMO, C is making unsubstantiated assumptions, something you never have to do in an actual GMAT CR question.

rahultgsp · Answer

guys the ans seems to be C
the explanation that i've found follows

Here's the explanation: We need to resolve the discrepancy that:

1) Authorities have posted signs to warn people to be more careful about pickpockets 
2) Since that point, pickpocketing has actually INCREASED

What C does (or attempts to do) is link the two together by saying that the signs actually provoke potential victims to signal the locations of their possessions to potential thieves by rummaging in their pockets, therefore making it easier for pickpockets to locate the items they want to steal.

Now, I've heard about this in the news and have actually caught myself patting my wallet to make sure it's still there in response to signs like that, so I was looking for something just like choice C when I read this. I wonder if this question wouldn't be filtered out of the official GMAT pool for that reason. Here I'd say:

-If someone has heard this warning before, they'll get this right without thinking 
-If not, C may not perfectly bridge that link between "riders rummaging" and "signaling to thieves" as well as it needs to.

So I'd just look at this as a great practice problem that probably wouldn't make the official test.

parker · Answer

Hey all,

I actually agree that you shouldn't rule out stuff based on stereotypes (or "commonly-known" info) -- what you should do is be *suspicious* of them. Elimination should always be based on concrete wrongs-- it is far easier to eliminate what's wrong that try to defend what's right. But I find that commonly-held, not-necessarily-true assumptions are often huge  traps  for students, especially ones who don't have a lot of experience with the test, because to newbies "correct answer" sometimes correlates with "yeah, I agree with that!" Of course, the more familiar with the test a student gets, the more ruthless and specific he or she is able to be about what piece of an answer choice knocks it out.

Sorry if that wasn't clear (and I can see why from my language it may not have been). I think almost all rules about "if you see this, rule it out *automatically*" are bogus--I see that kind of thing a lot more with sentence correction ("Oh, 'being' is there so it must be wrong!") but the higher up the score scale people get, the less useful that will become. Make sure as you study, especially past the 600 level, to differentiate between things that are concretely wrong based on RULES (eliminate pronto) and things that are often wrong because of TENDENCIES (be suspicious of, and exercise extra care when evaluating).

Here, the actual ruling out for me of  A  was because the fact that these people are tourists is not necessarily related to whether or not they will be more easily pickpocketed-- that distractor feeds on a stereotype that a lot of people have about tourists...a *common* assumption, which is not necessarily a *justified* assumption for this population. Ian's quite right that there could be a population  change  (A) or  increase  (B), which might make it easier for pickpockets. But  how much  of an increase would justify a two-fold increase the per capita rate of pickpocketing? Even for B, we'd have to assume a linear relationship between number of riders and pickpocketing rates.

I nixed D because there are some other obvious plausible reasons for fewer pickpockets being prosecuted/convicted...city budget cuts, policy priority shifts.

There are *definitely* assumptions being made in C. But the size of the leap being made seem smaller to me-- nothing needs to change about the constitution of the population, so even if we're starting with an identical baseline, and riders "tend to" do a behavior that makes the act of pickpocketing much easier, then those riders, even within a comparable population, would certainly be easier targets. And because the language used implies that a significant proportion of the riders walking past these signs exhibit this behavior (" Riders tend to " rather than " some  riders tend to," or "riders  may ," etc), I'd lean toward that choice helping to explain a two-fold increase more than the others.

Is it perfect explanation? Absolutely not--and the question asks which choice "helps to explain"-- we have all kinds of variables and assumptions for all the choices, but given the array of options I vote for it being most direct. And Rahul brings up an interesting point, although again (and that's why I'm really glad Ian brought up the point above--it's an important distinction, and my previous post wasn't clear about it-- the ultimate call is about what most directly explains with the fewest assumptions. If this were a GMAT question, and enough people got it right for the wrong reasons, it would probably be considered of "lower level" difficulty. Difficulty is a function of how many people (and which people) get a question right/wrong, which simply means clicking the right bubble. I can think of at least one math question in the OG that seems quite challenging for many, but has a low-number because so many people get it right for the wrong reason.

That said, I agree that the question could be improved, and I think it should have been along the lines that Gottesschaf mentioned--in a perfect world I'd like to see the discrepancy pointed to in the question rather than just "the discrepancy pointed out in the passage"-- but dealing what's there, I still vote C.

jko · Answer

I agree that this is a very awkward question.

If you're evaluating the statement:
"people rummage through their pockets or feel through their clothes to verify the presence of their possessions"

There are two perfectly logical conclusions you can come to from that.
1) As the OA indicates, pickpockets watch this and now have a better idea where the valuables are...
Weaknesses of this conclusion:
a) women keep their valuables in their purse, and men keep their wallet in a back pocket (which is easily visible), and their cell phone in a pocket or visible on a belt loop. I don't consider there to be that many unknowns in the 'where to people keep their valuables' game.
b) after seeing the signs, regardless of whether pickpockets know where to look for the valuables, people have already in the signs, have already had the fear of pickpockets instilled in them, and are now significantly more attentive to their possessions. This would likely make pickpocketing more difficult than if the target hadnt seen the sign and hadnt rummaged through his/her pockets.

2) People rummage through their pockets, know exactly where their goods are, and are now on double guard for those pockets which hold valuables.
Weaknesses:
a) Pickpockets know where to look...

Honestly, if you put someone (person A) in a crowd and tell them that pickpockets are prevalent in the area, and then put a pickpocket in the crowd and tell them exactly where person A has their valuables, my money says that pickpocket will not be successful.

When I was doing the problem originally, I came to conclusion (2), and discredited (C) because it did nothing to explain the paradox.

bhandariavi · Answer

I don't think we are allowed to make such a deep assumption in the real GMAT CR question.

MacFauz · Answer

I picked C. But my reasoning was as below :

The concern is about being pick pocketed AT the central station.

Suppose i'm at the central station and i have had my pocket picked, if i happen to check my pockets while i'm still at the central station and find my wallet missing, I would report that i got pick pocketed AT the central station.

However, if i wait until i get home or even until i leave the central station to check my pockets, I might think that i had been pick pocketed somewhere else.

vivmechster · Answer

Thanks VerbalBot
Though I chose (b), but then I realized "Per Capita" = no. of incidence/no. of people. Per capita increase means either numerator increase or denominator decrease.
So, C

Last year, after the number of subway riders who had had their pockets

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GMAT Critical Reasoning (CR) Questions

Last year, after the number of subway riders who had had their pockets

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