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Critical Reasoning: Correlation-Causation — Weaken Question 2

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In the previous post, we saw how Critical Reasoning questions on the GMAT® are based on rules of formal logic. We took the specific case of the arguments that incorrectly assume that correlation implies causation.

Just to summarize, X and Y are correlated does not mean X is causing Y since

  1. there is no evidence to prove that the direction of causation is from X to Y, it can also be from Y to X
  2. there can be a different reason, Z, for the occurrence of Y.

So based on arguments that conclude that X is causing Y since X and Y are correlated, there can be three types of questions that can be asked — Weaken, Assumption and Strengthen.

Weaken Type: Correct Option will always show that in fact Y is causing X (third cause Z is usually not given in the options since it will make the answer two obvious)

Researchers have concluded from a survey of people aged 65 that emotional well-being in adulthood is closely related to intimacy with siblings earlier in life. Those surveyed who had never had any siblings or who said that at college age they were emotionally distant from their siblings were emotionally less well adjusted at 65 than were those who had been close to at least one brother or sister.

Which of the following, if true, most seriously weakens the researchers’ argument?

(A) As they get older, many people think more about their mortality and thus must confront feelings of loneliness and isolation.
(B) People suffering from the emotional distress of maladjustment usually remember being less intimate with other people than they actually were.
(C) Memory of one’s past plays a greater role in the emotional well-being of older people than it does in that of younger people.
(D) Siblings are more likely to have major arguments and deep differences of opinion at college age than at any other time of their lives.
(E) Few people can correctly identify the true sources of their emotional well-being or of their emotional difficulties.

In this particular study, researchers have found that intimacy with siblings earlier in life (X) is closely related (correlated) with emotional adjustment later in life (Y). How did the researchers arrive at this conclusion? Read More

Understanding the GMAT Test Structure

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What do they know of cricket who only cricket know — from Beyond A Boundary by C. L. R. James

While the GMAT structure is quite well known to most test-takers there is much more to the test than meets the eye. Let us try to understand this a bit better since understanding the nature of the test will really help you get the right perspective for your preparation and practice with the right purpose.

What you get when you pay $250 to take the GMAT

What you get is a statistically valid and universally understood measure of your aptitude (as defined by the GMAC, an association of business schools) for doing a business course.

If you take the test today in India and score a 720 and 4 years later someone takes the test in China and scores a 720, schools will accept both of you as having the same aptitude — the 94th percentile. The scores and percentiles have barely changed over all of these years since about 2,50,000 people take the test every year.

Indian GMAT-takers need to understand this precisely since unlike Indian tests like the CAT, the GMAT is not a test of elimination but a measure of your aptitude. Thus, while a 720 on the GMAT means something precise, the same cannot be said about a score on the CAT — there is no standardized score to percentile conversion.

Also on the CAT since difficulty levels, questions types and number of questions vary drastically from year to year, it cannot be statistically proven that people getting 99’s in different years have the same aptitude. This is not a problem for the Indian schools since the CAT is not intended to provide test-takers with a valid measure of their aptitude, it is for institutes to eliminate a bulk of the approximately 2,00,000 test-takers appearing for the CAT every year.

Given the fact that the GMAC is an American association and hence would be bound by the American legal system, the test has to be developed, administered and scored in a way that makes the final score, which is valid for 5 years, lawsuit-proof!

How Do They Make This Measure Accurate?

How can two students who take the test years and countries apart be deemed to have the same aptitude? The answer lies in the format and content of the questions that the GMAT poses.

The question types, the number of questions and the concepts tested are so fixed that what actually changes is only the wrapper of the question — the specific content — the kind of logic/concept that is tested and the way in which it is tested do not change.

The GMAT Structure

GMAT STRUCTURE

The GMAT allows you to choose one of three pre-set section orders:

  • Analytical Writing Assessment, Integrated Reasoning, Quantitative, Verbal
  • Quantitative, Verbal, Integrated Reasoning, Analytical Writing Assessment
  • Verbal, Quantitative, Integrated Reasoning, Analytical Writing Assessment

Standardization runs right down to question-level

The GMAT is precisely defined not only at an area-level, but also at a question-type level. For example, within Critical Reasoning there are fixed question-types like Weaken, Strengthen, Conclusion, Assumption and Inference and so on with a fixed number coming from each type. The same is the case both with the errors tested on Sentence Correction and the topics tested on the Quantitative section.

Everything is transparent, except…

As mentioned earlier since the test functions in an American legal system everything has to be clearly defined which is why the GMAC not only provides information about the test but also releases loads of preparatory material and mock tests itself, something unheard of in India!

The only thing that the GMAC does not reveal is the algorithm of the GMAT.

Not just computer-based, it is a computer-adaptive test

One of the unique things about the GMAT is that it is a computer-adaptive test — a test where questions are calibrated to the level of test-taker. So, easy questions are not posed to a test-taker who is likely to get a high score and tough questions are not posed to a test-taker who is not likely to do well on the test.

Hence, everything hinges on the level of the test-taker, which the algorithm predicts.

The test will thus start with a question of moderate difficulty. If the test-taker answers it correctly, the algorithm poses a question of slightly higher difficulty and if the test-taker answers it incorrectly then the algorithm poses an easier question. The best analogy that we can use to understand the adaptive nature of the test is to think of it in weightlifting terms.

You are given a moderate weight and you lift it, the next weight you will have to lift will be slightly heavier, if you fail, the weight after that goes back to the previous level. So you can see that eventually you will hit the threshold beyond which you cannot lift.

A great test of competence

The beauty of the GMAT is that despite the fact that everything is so transparent and so many actual old questions are available for practice, the test is not a cakewalk with only 2% of the takers likely to score a 750 or above.

Every question-type needs to be tackled with a precise strategy. For example, there is a foolproof test on how to solve the Assumption question type on Critical Reasoning. Once a test-taker understands this properly, there is only a certain amount of practice that he or she would need — in my opinion not more than 20 questions to ensure that 9 out of 10 times you get an assumption question right. The specific content of the question becomes just a wrapper once you have mastered the underlying algorithm

The same applies to all other question types tested on the GMAT.

So how should you approach your GMAT Prep?

In terms of preparation, quality of practice becomes much more important than quantity of practice. A lot of test-takers preparing for the GMAT erroneously believe that just solving more and more questions will bump up their score. Nothing could be farther from the truth. The GMAT is a test that demands very limited but intense and precisely targeted preparation rather than an extended prep involving endless practice.

In terms of solving questions correctly, the GMAT rewards those who have a process-oriented approach rather than an intuition or common-sense based approach (the reason this needs to be mentioned is that areas like Critical Reasoning lull test-takers into believing that it is about common-sense).

Horses for courses

Many years ago I was discussing with a batch-mate of mine about how the GMAT and the CAT are actually well-suited tools to test aspirants’ potential for becoming business managers in developed economies and in India respectively.

In a developing country like India where the markets in most industries are not yet fully mature and systems & processes are not fully in place, the skill sets that are most critical are the ability to navigate unstructured environments, a certain tolerance towards uncertainty and the resourcefulness to improvise — this is exactly what the CAT given its unpredictable nature measures without necessarily intending to.

In mature markets like the US, business managers need to function and execute plans in a highly structured environment with competence, which is exactly what the GMAT tests, rather than resourcefulness being the key.

And most of us would know the famous Indian word for resourcefulness — jugaad, which the last thing you should use for your GMAT prep if you plan to ace the test!

 

 

 

 

Sentence Correction – Comparatives 2

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In the previous Sentence Correction post, we saw how it is important to listen for structure in order to get SC questions on the GMAT right. We took one type of structure, which involves making the right comparison, and saw how it is tested on the GMAT. Let us look at a few more questions of the same type but varying difficulty levels.

EASY
Unlike Schoenberg’s 12-tone system that dominated the music of the postwar period, Bartok founded no school and left behind only a handful of disciples.

(A) Schoenberg’s 12-tone system that dominated
(B) Schoenberg and his 12-tone system which dominated
(C) Schoenberg, whose 12-tone system dominated
(D) the 12-tone system of Schoenberg that has dominated
(E) Schoenberg and the 12-tone system, dominating

In this question, the original sentence sentence incorrectly compares Schoenberg’s 12-tone system with Bartok; the correct option has to compare Schoenberg to Bartok, which only option (C) does. The sentence is relatively short and the comparison is easy to identify so this is an easy question that can be solved in around 45 seconds. Read More

Data Sufficiency — The C-Trap 2

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In the previous post we saw how Data Sufficiency questions on the GMAT can be deceptively tricky in that they lure test-takers into choosing Option C. Let us have a look at another  Data Sufficiency question that makes test-takers commit the same error.

Each data sufficiency problem below consists of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you are to option

A if statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked;
B if statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked;
C if BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient;
D if EACH statement ALONE is sufficient to answer the question asked;
E if statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.

The difference between Mary and Jim’s salary was twice the difference between Mary and Kate’s. If Mary had the highest salary, what was the average of the three?

(1) Jim’s salary was $30,000
(2) Kate’s salary was $40,000

Most test-takers start the problem by taking M, J & K as the salaries of the three individuals and they form the equation : M – J = 2 (M – K).

They look at the two statements and decide that since from the two statements they are getting the values of M and K, they can use the equation above to calculate the value of J. Once they have all the three salaries, they can calculate the average salary, hence , C! Read More

Sentence Correction – Comparatives 1

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While solving Sentence Correction questions, a lot of test-takers rely on their ear to give them the answer, which is why one often hears the phrase, “this option doesn’t sound right”.

While the ear does play a very important role, it more important to listen with a purpose. When it comes to Standard Written English, which is what is tested on the GMAT as well as other tests, it is important to listen for structure.

Different sentences have different structures based on their construction. In this post, let us look at one type of structure, comparatives, with help of a sentence correction question from the Official Guide (OG).

Unlike the buildings in Mesopotamian cities, which were arranged haphazardly, the same basic plan was followed for all cities of the Indus Valley: with houses laid out on a north-south, east-west grid, and houses and walls were built of standard-size bricks.

(1) the buildings in Mesopotamian cities, which were arranged haphazardly, the same basic plan was followed for all cities of the Indus Valley: with houses
(2) the buildings in Mesopotamian cities, which were haphazard in arrangement, the same basic plan was used in all cities of the Indus Valley: houses were
(3) the arrangement of buildings in Mesopotamian cities, which were haphazard, the cities of the Indus Valley all followed the same basic plan: houses
(4) Mesopotamian cities, in which buildings were arranged haphazardly, the cities of the Indus Valley all followed the same basic plan: houses were
(5) Mesopotamian cities, which had buildings that were arranged haphazardly, the same basic plan was used for all cities in the Indus Valley: houses that were

By GMAT standards this is quite long sentence and would cost most test-takers more than the average time available, 1:49 seconds. But if one listens to the structure it can be solved in less than a minute. Read More

Problem Solving – Logic Not Formulae

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A lot of test-takers feel that like for other tests for the GMAT Quantitative as well they need to learn a lot of formulae. They often come and tell us they are revising all the formulas in the last few days before the test; nothing could be more superfluous since very few GMAT problems actually test your knowledge of formulas apart from problems involving Geometry.

What is evaluated your ability to reason in a quantitative context as this question from the Official Guide (OG) illustrates.

If s and t are positive integers such that s/t=64.12, which of the following could be a remainder when s is divided by t?

(A) 2
(B) 4
(C) 8
(D) 20
(E) 45

Many test-takers are flummoxed by this problem because they do not know what to do with it! They quickly realize that there is no formula they can apply and that they only have their wits to rely on.

So how does one approach it? Read More

Critical Reasoning: Correlation-Causation — Weaken Question 1

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The biggest misconception about Critical Reasoning questions on the GMAT® is that they are based on common sense. Well, nothing could be farther from the truth. In fact, CR questions are based on rules of formal logic. The question from the Official Guide (OG) below is a perfect illustration.

A study of marital relationships in which one partner’s sleeping and waking cycles differ from those of the other partner reveals that such couples share fewer activities with each other and have more violent arguments than do couples in a relationship in which both partners follow the same sleeping and waking patterns. Thus, mismatched sleeping and waking cycles can seriously jeopardize a marriage.

Which of the following, if true, most seriously weakens the argument above?

(A) Married couples in which both spouses follow the same sleeping and waking patterns also occasionally have arguments that can jeopardize the couple’s marriage.
(B) The sleeping and waking cycles of individuals tend to vary from season to season.
(C) The individuals who have sleeping and waking cycles that differ significantly from those of their spouses tend to argue little with colleagues at work.
(D) People in unhappy marriages have been found to express hostility by adopting different sleeping and waking cycles from those of their spouses.
(E) According to a recent study, most people’s sleeping and waking cycles can be controlled and modified easily.

The question seems like a real-life situation that has nothing to do formal logic; test-takers typically tend to choose option A. Not if you start reading CR questions differently. Read More

Data Sufficiency — The C-Trap 1

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Data Sufficiency questions on the GMAT® , are often the bugbear for most test-takers. While Problem Solving is straightforward, Data Sufficiency is at its most trickiest when it is seems to be straightforward.

Each data sufficiency problem below consists of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you are to option

A if statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked;
B if statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked;
C if BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient;
D if EACH statement ALONE is sufficient to answer the question asked;
E if statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.

If each pencil is either 23 cents or 21 cents, how many 23 cent pencils did Martha buy?
(1) Martha bought a total of 6 pencil.
(2) Total value of pencils Martha bought was 130 cents

Most test-takers start the problem by taking x and y as the number of 23-cent and 21-cent pencils bought by Martha. Read More