CR - Strengthen the argument

Question

Critical Reasoning - Strengthen the argument resources.  
  Question format:

Which of the following strengthens/ supports/ most justifies/ helps…

Characteristics of Strengthen the conclusion question

Ask to support conclusion/argument in any way- answer can support in a minor or major way! 
  Stimulus will always be an argument- since you can only strengthen a conclusion, not a fact set. Identify, isolate and assess the premises and conclusion. 
  Focus on conclusion. 
  Information in stimulus is suspect. Reasoning errors are present which can be corrected by answer choice. 
  Strong prephrases possible 
  Answer choices can bring new information which is not present in stimulus. 
  While an assumption is necessary to the argument, a strengthen answer might not be essential for the argument to be true. 
  The correct answer will , at least somewhat, venture outside the scope of the immediate argument (i.e. introduce something new)

How to strengthen?

• Identify the conclusion – your answer choice should help the author and his conclusion
• Personalize the argument- place yourself inside the situation and think how you will react.
• Look for weaknesses in the argument – any gap, hole- that is tailor made to be eliminated as a correct strengthen answer. 
• An answer that highlights an assumption of the author will also strengthen the author’s conclusion
• If the argument stimulus talks of a survey, poll- any answer choice which highlights its soundness or establishes its credibility will be correct.
• Correct answer can strengthen just a little or a lot!

Correct answer will strengthen by:

• Fixing a weakness of the conclusion
• Validate an assumption made by argument
• Introduce additional supporting evidence

Incorrect answer types:

• Opposite answers: Weaken
• Shell Game answers: idea form stimulus altered a little to be wrong
• Out of scope answer: miss the point/conclusion
 
 Whenever a stimulus starts with word ‘Advertisement:’ it will have flawed logic. Be prepared to look out for the gap and address that.

Causality and Strengthen Question

• Eliminate alternate causes
• Show that when the cause occurs, effect occurs
• Show that when the effect is there, cause has occurred
• Show that reverse is not true
• Show that statistical data behind the cause effect conclusion is correct
• Show that when cause doesn’t occur, effect doesn’t occur

In StrnegthenX questions, correct answer choice will mostly have no effect on the argument, or will be out of scope. Be cautious sometimes the answer choice which strengthens the argument is wrongly selected if it strengthens by eliminating an alternate cause which doesn’t occur in stimulus. There is tendency to think that it is out of scope and doesn’t strengthen. E.g. in a question that argues that amphibian population is decreasing because of ozone depletion, an answer choice that their natural habitat is not depleting is not out of scope- but strengthening by eliminating alternate cause of fall in population

BEST APPROACH: SIMPLIFY THE ARGUMENT INTO 1-2 STATEMENTS, and apply choice ONLY to simplified argument. Many choices that seemed relevant otherwise will now not be relevant!

GMATPREP EXAMPLE Q. Excavation of the ancient city of Kourion on the island of Cyprus revealed a pattern of debris and collapsed buildings typical of towns devestated by earthquakes. Archaeologists have hypothesized that the destruction was due to a major earthquake known to have occured near the island in A.D. 365. Which of the following, if true, most strongly supports the archaeologists' hypothesis?
(A) Bronze ceremonial drinking vessals that are often found in graves dating from years preceding and following A.D. 365 were also found in several graves near Kourion.
(B) No coins minted after A.D. 365 were foundin Kourion, but coins minted before that year were found in abundance
(C) Most modern histories of Cyprus mention that an earthquake occured near the island in A.D. 365.
(D) Several small statues carved in styles current in Cyprus in the century between A.D. 300 and 400 were found in Kourion.
(E) Stone inscriptions in a form of the Greek alphabet that was definitely used in Cyrpus after A.D. 365 were found in Kourion

Simplified: an earthquake destroyed city. The earthquake happened in year 365. C says that the earthquake happened – that doesn’t strengthen, this is already known to have occurred from the question stem. Reiterate something that is already known – DOES NOT strengthen.

B pinpoints the date at year 365. Correct.

B pinpoints the date at year 365. Correct.

Notes Credit: Vivesomnium, Ron Purewal, Powerscore CR Bible, GMATPrep 2.0

Strengthen/Weaken Resources    How to Get CR Weaken Right Every Time  - Manhattan GMAT 
  Strengthen Strategy and Set  
  Weaken Strategy and Set  
  Thursdays with Ron Strengthen/Weaken Part I  
  Thursdays with Ron Strengthen/Weaken Part II  
  An Architect's Look at Critical Reasoning  - VeritasPrep Director Bryan Galvin makes it impossible for anyone to miss a CR question

souvik101990 · Answer

Strengthen/Weaken exercise

The prairie vole, a small North American grassland rodent, breeds year around, and a group of voles living togather consists primarily of an extended family, often including two or more litters. Voles commonly live in large groups from late autumn to winter; from spring thru early autumn, however, most voles live in far smaller groips. The seasonal variation in groups size can probably be explained by a seasonal variation in mortality among young voles.

Which of the following, if true, provides the strongest support for the explanation above?

A) It is the spring and in the early summer that prairie vole communities generally contain the highest proportion of young voles. 
B) Prairie vole populations vary dramatically in size from year to year. 
C) The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring. 
D) Winters in prairie vole's habitat are often harsh, with temperatures that drop well below freezing. 
E) Snakes, a major predator of young prairie voles, or active only from spring thru early autumn.

I will post answer and explanation tomorrow. Let's get this party going. 
 This is an official question. Please do not google. Try it yourself.

Carcass · Answer

I would be the less indicated to answer to this CR. Waiting other responses before elaborating my answer.

Good job as usual from you

rrsnathan · Answer

I would like to answer to this
I pick E

Conclusion:  The seasonal variation in groups size can probably be explained by a seasonal variation in mortality among young voles
Which says the seasonal variation in group soze is explained by variation in mortality rate caused seasonally
  Assumption : 1) either they die because of season change (or) Die because of some natural (or) split and live because of their nature for each season

So i picked E.

Waiting for Answer

Thanks,
Swami.

PiyushK · Answer

IMO E.

Only E explains the seasonal factor which reduces vole population between sprig and autumn.

C and D need too much assumptions to churn out the connection between seasonal population change.

A and B does not address seasonal population change.

pratyushakosaraju · Answer

I have recently given my GMAT official exam. I got this exact question in my GMAT verbal section and i answered option E. It it the correct answer?

CrackverbalGMAT · Answer

The right answer here should be E. When you look to support a conclusion, you should first identify what that conclusion is. In this case, it's that "something affects the population in spring - autumn".

Hence, we want an answer that either suggests the population will be lower in the spring, or that will be higher in the winter.

Once you eliminate the opposites and irrelevant answers, E is all you should have left.

- Matoo

OhsostudiousMJ · Answer

The question says the seasonal variation in group sizes can probably be explained by seasonal variation in mortality among young volves, and for me, option D answers this. The extremely low temperatures in winters is what increases the mortality rate of young volves. Additional information strengthening the conclusion of the statement.

I would avoid option E, as the use of "only" makes it too extreme.

Thoughts?

I would avoid option E, as the use of "only" makes it too extreme.

Thoughts?

CrackverbalGMAT · Answer

OhsostudiousMJ 
When you look to eliminate an extreme answer choice, do not do so solely on the basis of the presence of a word like only, or always. What you have to consider is the meaning and implication of the statement itself. You're not looking to suggest whether the option is "true" or not, you are looking to analyse how it impacts the argument.

In  E , when it says "only present in the spring", what it tells us is that it's not there in the other time of the year, when the voles are many. So when the snakes are active, the voles are few, when they are not, the voles are many. This is a statement that clearly supports the idea that there is a mortality from spring to autumn.

D  in fact suggests the opposite of what we are looking for. Sure, harsh winters means few voles in the winter. But this is precisely when we've been told that there are many of them. So if anything, this suggests that the winter has no effect.

- Matoo

OhsostudiousMJ · Answer

Thanks for the response.

I understand now. I had misunderstood the question initially.

VerbalBot · Answer

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CR - Strengthen the argument

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GMAT Critical Reasoning (CR) Questions

CR - Strengthen the argument

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