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Passage Topic

The distribution of passage topics hardly changed. There are 2 fewer biology passages, but we should expect some normal variation from edition to edition.

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Difficulty Distribution
This graph displays the difficulty level of problems that were removed, repeated, and added. Excluding problems in the Diagnostic exam, higher-numbered problems are more difficult, according to the GMAT. On the left, red problems were removed from the 11th edition. On the right, dark-green problems were added to the 12th edition. Light colors are repeats, as shown by a few correspondences in the middle.



Seven passages at all levels of difficulty were removed, together with all their problems. Moreover, two problems were removed from passages that were retained. These problems contained statements or phrases labeled with Roman numerals (I, II, III). Since no other problems contain Roman numerals, the GMAT seems to be indicating that it is moving away from such problems.



No new problems were added to old passages. The only source of new problems is new passages, which are distributed at all levels of difficulty.



Since questions must be listed together with their passages, note that “easier” passages could have hard questions associated with them, and vice versa.


 
If we accept that the passages are listed in order of difficulty, then difficulty is somewhat correlated with length and with topic in the 12th edition, just as it was in the 11th edition. High-numbered passages are more likely to be long; low-numbered passages are more likely to be short. However, the correlation is far from perfect.

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Moreover, business passages tend to be lower-numbered. Biology and social science passages are relatively evenly distributed, and physical science passages tend to be higher-numbered. Again, though, this is a statistical pattern. Topic is not a perfect predictor of difficulty or position.



These graphs look essentially the same for the 11th edition.



Are higher-numbered passages truly more difficult? You should regard this issue with some degree of skepticism for the following reasons:

Passages have similar measures on other objective measures of difficulty besides length and topic (e.g., words per sentence). Moreover, there is no significant correlation between those objective measures and position in either the 11th or the 12th edition.
The effective difficulty of a passage depends a great deal on you – that is, on your personal comfort level with the topic. You are not expected to bring specific scientific knowledge to bear on the GMAT. But if you are interested – or become interested – in the content of a passage, you will find that passage much easier to digest, whether the passage is considered difficult or easy by the GMAT.
Qualitative Observations
Reading Comprehension has not really changed. The content and style of the new passages and questions is very similar to the content and style of removed passages and questions.
As was mentioned earlier, Roman-numeral questions have been deleted. Since the associated passages were retained, together with all the other problems, this deletion is a fairly strong signal that the GMAT may be moving away from this sort of question. However, there were only 2 such questions in the 11th edition; this type of problem was never very important.

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Official Guide 12th Edition: Data Sufficiency
<< Back to 12th Edition Overview
            
Overall Changes
Which Problems Changed?
For an exact list of differences between the 11th and 12th editions, download the Data Sufficiency Problem List.Observations

The 11th edition has 179 Data Sufficiency problems (including 24 Diagnostic problems). In the changeover to the 12th edition, 75 problems were removed, leaving 104 repeats (including all Diagnostics), and 94 problems were added, yielding 198 Data Sufficiency problems in the 12th edition.


Analysis

Among the question formats, Data Sufficiency has the highest proportion of new problems (47%). This section also grew by 19 problems, much more than any other question format. (At the same time, Problem Solving decreased by 19 problems.) These changes could reflect an increased emphasis on this problem type.

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Topic Distribution


Analysis

The number of Word Translations questions (word problems of various types) has grown significantly, particularly among the Statistics and non-specific Algebraic Translations topics. Meanwhile, the number of pure Algebra problems (especially Inequalities and Basic Equations) has fallen substantially.



The GMAT has a number of different obstacles at its disposal to hide what information is needed to solve Data Sufficiency problems. This analysis suggests that the GMAT may be shifting towards word problems as the preferred Data Sufficiency obstacle. Furthermore, the GMAT may be shifting away from pure Algebra as the preferred obstacle.



However, we must caveat that you should not over-interpret this change. Some variation is to be expected. Also remember that you generally need pure Algebra skills to solve Word Translations problems. After you've translated the word problems into algebra, you must often use algebraic manipulation to complete the analysis.

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Difficulty Distribution
Observations

This graph displays the difficulty level of problems that were removed, repeated, and added. Excluding problems in the Diagnostic exam, higher-numbered problems are more difficult, according to the GMAT. On the left, red problems were removed from the 11th edition. On the right, dark-green problems were added to the 12th edition. Light colors are repeats, as shown by a few correspondences in the middle.


Analysis

In the Data Sufficiency section, primarily Easy and Medium-Hard problems were removed; however, problems of all difficulties were deleted. In some cases, groups of 4 or 5 problems were removed or preserved at a time. Additions were made at all levels of difficulty, but not quite as many at the highest end.


Qualitative Observations
Several of the new Word Translations problems require that you keep track of 3 or 4 variables. Sometimes, you are given variables (often with subscripts, such as p1 and p2). In other cases, you must name the variables yourself and/or keep track of them in a table.
Many new problems impose constraints on variables. Often, variables are restricted to positive values explicitly (x > 0) or implicitly (x is the tax rate). A few problems impose an integer constraint as well (x is the number of cookies). As you solve for the variable – or, better, as you determine whether you can solve – remember to take these constraints into account. For instance, a quadratic equation may have two solutions, but if one solution is negative, it may be invalid. In this case, you would then have sufficiency, because only the positive solution is valid.
Many new problems require manipulation of inequalities in some way, even though the number of problems classified as “Inequalities” has decreased. The GMAT may be shifting this topic to more of a word-problem format. In most of the new 12th edition problems, the variables turn out to be restricted to positive numbers (see the previous point). In fact, the GMAT has removed many inequality problems that required you to deal with both positive and negative cases in the same problem.

Many new problems require statistics knowledge and skills. Topics such as weighted averages and medians continue to grow in importance.

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GMAT Official Guide 12th Edition: Problem Solving
<< Back to 12th Edition Overview
            
Overall Changes
Which Problems Changed?
For an exact list of differences between the 11th and 12th editions, download the Problem Solving Problem List.The 11th edition has 273 Problem Solving problems (including 24 Diagnostic problems). In the changeover to the 12th edition, 75 problems were removed, leaving 198 repeats (including all Diagnostics), and 56 problems were added, yielding 254 Problem Solving problems in the 12th edition.


Among the problem formats, Problem Solving has the lowest proportion of new problems (22%). This section also decreased by 19 problems, a larger decrease than any other question format. (At the same time, Data Sufficiency increased by 19 problems.) These changes could reflect a slight shift toward Data Sufficiency on the Quantitative section of the GMAT.

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Topic Distribution

The proportion of problems in various topical categories has not changed substantially. The most significant change is that problems classified as Fractions, Decimals, & Percents have decreased somewhat in number. However, this very slight decrease does not mean that this topic has become less fundamental. Remember, slight variation is to be expected.

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Difficulty Distribution
This graph displays the difficulty level of problems that were removed, repeated, and added. Excluding problems in the Diagnostic Exam, higher-numbered problems are more difficult, according to the GMAT. On the left, red problems were removed from the 11th edition. On the right, dark-green problems were added to the 12th edition. Light colors are repeats, as shown by a few correspondences in the middle.

Moving up the numbers, we see that the removals and the additions essentially correspond for most of the problems. Some “Medium-Easy” problems were removed, but they were replaced by Easy and Medium problems. The big discrepancy comes at the Hard end of the 11th edition. A batch of difficult problems was removed but not replaced. This accounts for the decrease in the overall number of Problem Solving problems.



A few relatively long stretches of problems were left unchanged. Generally, problems were removed or added in very small groups or individually.

Qualitative Observations
While there are several interesting and well-written new problems, the content of the Problem Solving section has not fundamentally changed.
The only shift truly worth noting is relative to Data Sufficiency. Since the number of Problem Solving problems has fallen (and many hard problems were actually removed), the GMAT may be moving in the direction of increasing the number of Data Sufficiency problems on the test.

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