Overall Changes

The 11th edition has 156 Sentence Correction problems (including 18 Diagnostic problems). In the changeover to the 12th edition, 55 problems were removed, leaving 101 repeats (including all Diagnostics), and 57 problems were added, yielding 158 Sentence Correction problems in the 12th edition – 2 more than in the 11th edition.

The proportion of new Sentence Correction problems (36%) is very nearly the same as the average for all problems (33%).

Topic Distribution

Classifying Sentence Correction problems under one category is a simplification, since most problems test more than one topic. That said, we have identified the primary topic tested by each problem and computed the total in each category, as shown below.

The proportion of problems in various categories has changed, but only slightly.

The number of Pronoun and Modifier problems has risen somewhat, while the number of Comparisons and Idioms problems has fallen by a similar amount. Parallelism has increased by 2 problems. Otherwise, the net number of problems in various categories has remained the same. Parallelism is still the clear leader as a primary topic, but Modifiers replaces Comparisons in the #2 position.

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 represent repeated questions.

Problems were removed from the 11th edition at all levels of difficulty. In some cases, groups of 3 or 4 problems in a row were deleted.

Problems were also added to the 12th edition at all levels of difficulty, but in an extremely regular pattern, with no more than 1 at a time. This pattern is the same as that for new Critical Reasoning problems.

The difficulty of various topics, as measured by position, shifted somewhat. The most substantial changes were among Comparisons, which increased moderately in difficulty, and Meaning/Concision, which fell in difficulty. Odds & Ends has a very small sample size, so the large swing of its position is not that meaningful.

Qualitative Observations

1. Like the other problem types, Sentence Correction has not changed greatly from the 11th to the 12th editions. Do not forget this point as you study the nuances of new problems.
2. The GMAT continues to look for ways to penalize unwarranted shortcuts. Certain awkward expressions are often but not always wrong, and the GMAT has included problems that force you to choose these expressions, such as being (in #101) or the fact that (in #83). Remember that the right answer is not necessarily graceful, but it must be grammatically correct.
3. Explanations for repeated problems have generally remained the same, but occasional changes have been made that may indicate a slight refinement in the GMAT's thinking on particular issues. For instance, the explanation for problem #7 in the 11th edition condemns the use of which in restrictive clauses and instead insists on the use of that. This problem has been preserved verbatim as #10 in the 12th edition, but now the explanation says that the rule against which in restrictive clauses is "controversial." As it turns out, none of the wrong answers in the problem fail solely on this basis. Nevertheless, with its new explanation, the GMAT has signaled that it will almost certainly never write wrong answer choices that can only be eliminated with the which rule.
4. A few idioms have been added or returned to the working lexicon of GMAT Sentence Correction. Some of these, such as not just X but also Y, are variations of well-known idioms. Of course, you must be extremely careful not to draw too many analogies with idioms, which by definition resist classification. For instance, one new problem (#140) uses the word dated, which must go with at, not to be, when you express an age: This fossil has been dated AT 10,000 years old, not TO BE 10,000 years old. In contrast, a seemingly similar word, estimated, must be used in precisely the opposite way with ages (This fossil has been estimated TO BE 10,000 years old, not AT 10,000 years old), as is tested by problem #27 (#21 in the 11th edition).

Overall Changes

The 11th edition has 141 Critical Reasoning problems (including 17 Diagnostic problems). In the changeover to the 12th edition, 50 problems were removed, leaving 91 repeats (including all Diagnostics), and 50 problems were added, yielding 141 Critical Reasoning problems in the 12th edition – the same number as in the 11th edition.

The proportion of new Critical Reasoning problems (35%) is very nearly the same as the average for all problems (33%).

Topic Distribution

The proportion of problems in various categories has changed somewhat.

Two minor question types have substantially increased in number: Analyze the Argument Structure (from 3 to 13) and Evaluate the Conclusion (from 6 to 14). Analyze the Argument Structure problems include “boldface statement” problems, in which 1 or (usually) 2 statements within an argument are displayed in boldface, and you are asked to describe the role these statements play within the argument. The GMAT has added 9 such problems. Evaluate the Conclusion problems ask you to choose the best way to evaluate the validity of a conclusion, e.g. what information would be most useful to know. These increased numbers may indicate that the GMAT is emphasizing these particular types of problems more than before.

Among major question types, Weaken the Conclusion has fallen the most in number (from 51 to 37); however, it is still the most numerous question type. Both Find the Assumption and Draw a Conclusion have also registered declines; in fact, in the 12th edition, they are not much more prevalent than the growing minor types mentioned earlier. However, Find the Assumption and Draw a Conclusion should still be classified as major types, given their logical importance.

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 represent repeated questions.

Problems were removed from the 11th edition at all levels of difficulty. Every instance in which 2 or 3 questions were asked about 1 argument was eliminated. In some cases, every question was removed; in other cases, one question was preserved.

Problems were also added to the 12th edition at all levels of difficulty, but in an absolutely regular pattern, with no more than 1 at a time.

As for the difficulty of various question types, the average difficulty of Analyze the Argument and Evaluate the Conclusion fell, because more problems of each type were added throughout. Evaluate the Conclusion fell the most, since many low-numbered problems of this type were added. Among the major question types, Find the Assumption and Draw a Conclusion became moderately harder.

Qualitative Observations

1. The most interesting shift is the growth of the minor types, particularly Analyze the Argument Structure, as mentioned above. Analyze the Structure problems were under-represented in the 11th edition (in fact, only one boldface statement problem exists – and it’s in the Verbal Supplement, not the 11th edition itself). This problem type is generally difficult, since the arguments are generally long and complex, and the answer choices are often worded in confusing ways. Students should be sure to practice problems of this type. Also, Evaluate the Conclusion deserves additional attention, although the new problems are concentrated in the lower (easier) numbers.
2. An interesting new structure appeared in one Explain the Event problem (#22). In this problem, a plan is outlined, together with the result (the failure of the plan). Finally, further information is provided. This further information allows you to rule out some possible explanations for the failure of the plan.
3. Several new problems contain rather long chains of cause and effect (e.g., #49, 62, 112). Students will continue to need effective techniques for keeping track of complex arguments.

Overall Changes

The 11th edition has 158 Reading Comprehension questions in 27 passages. In the changeover to the 12th edition, 45 problems and 7 passages were removed, leaving 113 repeated problems and 20 passages (including all Diagnostic problems and passages). 43 problems and 7 passages were then added, bringing the total to 156 questions and 27 passages—almost exactly the same as in the 11th edition.

Among the problem formats, Reading Comprehension has the second lowest proportion of new problems (28%). New passages constitute a similar portion of the whole (26%).

Distribution of Questions and Passages

General vs. Specific Questions

The General/Specific split has not changed very much. Within the Specific category, there is a slight shift away from Detail questions (lookups) toward Inference questions, which require not only a lookup but also some degree of interpretation or further thinking.

Passage Length

Two long passages (>300 words) were replaced by two short passages (<250 words). However, the overall proportion is essentially unchanged, with a rough balance between long and short.

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.

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.

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

1. 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.
2. 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.

Overall Changes

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.

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.

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

1. 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.
2. 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.
3. 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.
   
4. Many new problems require statistics knowledge and skills. Topics such as weighted averages and medians continue to grow in importance.

Overall Changes

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.

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.

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

1. While there are several interesting and well-written new problems, the content of the Problem Solving section has not fundamentally changed.
2. 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.