Comparison Paradoxy

Question

Hello GmatClub,

Whenever I see a comparison type SC question, I was quick to narrow into the "than that in/of" answer. However, I'm starting to realize that it isn't as straightforward as that. May I stir discussion on this type of question.

Consider:

a. My exam performance was  better in 2010 than 2011 .  Clearly wrong .
b. My exam performance was  better in 2010 than in 2011 .  Seems right .
c. My exam performance was  better in 2010 than that in 2011 .  Seems right too .

Explanation: The "that" in c is implied in b and can be left out.

Now things get trickier if we're mixing tenses.

e. My exam performance is  better now than it was in 2011 . It refers to exam performance,  we're good .
f. My exam performance is  better now than that in 2011 .  Wrong  because the parallelism in e is missing. 
g. My exam performance is  better now than in 2011 .  What you guys think ?

Explanation: Because we are comparing now and 2011, we have to introduce the tense is / was. Because of this, we can't imply the pronoun like we did in b. I'm on the fence for g.

Lastly, let's wrap up with an actual GMAT example, which stumped me, and focus on the two near correct answers.

In 1979 lack of rain reduced India's rice production to about 41 million tons, nearly 25 percent  less than those of the 1978 harvest .
(A) less than those of the 1978 harvest
(B) less than the 1978 harvest

Answer is B. For me, the hard part of eliminating A is when I refer " those " to " rice production ". I know I can't do that because those is plural and production is singular. Correct? Things get really dicey if A instead read "than that in". So the answer will read:

In 1979 lack of rain reduced India's rice production to about 41 million tons, nearly 25 percent less than  that  (=  India's rice production ) in the 1978 harvest.

Looks correct to me.

As for B, is it okay to read the "harvest" in "nearly 25 percent less than the 1978 harvest" as "rice production"? Doing so convinces me that B is the correct answer.

Sincerely Yours,
Donny

mikemcgarry · Answer

Dear donnylee , I'm happy to respond.

Here are my comments on your examples. A. My exam performance was better in 2010 than 2011 . Yes, wrong . B. My exam performance was better in 2010 than in 2011 . Perfect! . C. My exam performance was better in 2010 than that in 2011 . Awkward, probably not a right answer on the GMAT . E. My exam performance is better now than it was in 2011 . Not bad . F. My exam performance is better now than that in 2011 . Awkward, doesn't sound good . G. My exam performance is better now than in 2011 . best! I would recommend this blog article: Dropping Common Words in Parallel on the GMAT That article explains the governing idea here. Here's your GMAT question, SC #9 in the OG 2012. In 1979 lack of rain reduced India's rice production to about 41 million tons, nearly 25 percent less than those of the 1978 harvest . (A) less than those of the 1978 harvest = wrong (B) less than the 1978 harvest = perfect, elegant Choice (A) makes the mistake of using " those " to refer to " 41 million tons ," but the comparison is not about a specific amount. This is a subtle logical mistake. Choice (B) compares harvest to harvest: clean, logically sound, succinct, elegant--a beautifully constructed answer in every way! Does all this make sense? Mike

EducationAisle · Answer

Hi  donnylee , this would be correct,  despite  the tense change.

A case in point is the following official question:

Heating-oil prices are expected to be higher  this year than last  because refiners are paving about S5 a barrel more for crude oil than they were last year.

Notice that there is again a tense  change  (in the  bold text  above), but the changed tense is just  implied .

p.s. Our book    EducationAisle Sentence Correction Nirvana    discusses  these comparison issues , their application and examples in significant detail. If someone is interested, PM me your email-id; I can mail the corresponding section.

donnylee · Answer

Hi EducationAisle,

Thank you for the follow up.

I'm used to resort to a formulaic technique when it comes to these sort of things. Is there anything wrong for me to think of the correct answer as:

Heating-oil prices are expected to be higher this year than  they were  last  year  because refiners are paving about S5 a barrel more for crude oil than they were last year.

and then drop the words (in  blue ) to give the answer?

I don't see anything wrong with the above sentence. And if given both the above and the correct answer, surely the I'll choose the correct answer due to economy of words. My prompt is for comments in thinking of an answer in this way: use the unabridged version as a check on its correctness.

EducationAisle · Answer

Hi  donnylee , this is correct interpretation.

Am pretty sure we would never see  both  of these in the options. However, your initial question was whether mentioning the verb is  mandatory , in case of a  tense change  after the comparison operator.

Hence, I cited the official example to illustrate that despite the  tense change  after the comparison operator, explicitly mentioning the verb (with correct tense) is  not  mandatory in all scenarios. These scenarios are detailed out in the comparison chapter of our book.

KarthikMBA2019 · Answer

Hi All,

I came across the below OG questions and found differences in the OG explanation which I am unable to comprehend.

OQ1: Prices at the producer level are only 1.3 percent higher now  than a year ago and are going down, even though floods in the Midwest and drought in the south are hurting crops and therefore raised  corn and soybean prices.

OE1: There is an illogical comparison between prices at the producer level and a time period (a year ago)

OQ2:  Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were  last year.

OE2: There is a comparison between this year's and last year's heating-oil prices.

Aren't both the explanations contradicting? What am I missing here?

Experts  mikemcgarry ,  egmat  ,  GMATNinja ,  KarishmaB ,  sayantanc2k ,  daagh ,  chetan2u 
Could you please help me?

KarishmaB · Answer

In question 1, the comparison is between prices and a time period. This is incorrect.

Question 2 option (A) is elliptical. 
The missing words could very well be 
... prices are expected to be higher this year than last  .

chetan2u · Answer

Karthik, I do not think there is anything wrong in the first part. It follows almost the same structure as the second sentence.
Having said that there must be some other errors in sentence 1 that make it wrong. And it is widely believed that although you can never doubt the answer but the explanations are not the best always.

If you are talking of ellipsis it can be done to both..

OQ1: Prices at the producer level are only 1.3 percent higher now  than - the prices at the producer level - a year ago and are going down, even though floods in the Midwest and drought in the south are hurting crops and therefore raised  corn and soybean prices.
 So nothing wrong here too. The choice is wrong basically for other reasons

ccooley · Answer

In my opinion, you're correct. We noticed this at MPrep a while ago and had a discussion about it - I don't think we ever came to a satisfying conclusion, except for 'sometimes the official explanations are misleading.'

In general, if you see something like this ('prices are 1.3 percent higher now than a year ago') in an official problem, look at the other issues first and eliminate whatever you can. If you end up with two answer choices that both seem otherwise correct, but one says 'a year ago' and the other says 'the prices from a year ago', go with the one that spells it out more clearly. But there will most likely be another, clearer issue to work with first.

EducationAisle · Answer

Hi Karthik, as others have correctly pointed out, there is nothing wrong in either of these sentences from a comparisons perspective; however, the official  explanations  are sometimes less than ideal.

In OQ1, the real problem is:  .....in the south are  hurting  crops and therefore  raised  .....  Hurting  is not parallel to  raised .

An officially  correct  sentence:

The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than when the use of DDT was sharply restricted in the early 1970’s.

Again, this is a  correct  sentence from a comparison perspective.

It would be wrong to consider that  its numbers  is being incorrectly compared with  when the use of DDT was sharply restricted in the early 1970’s .

The way to read this is:

The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than (its numbers were) when the use of DDT was sharply restricted in the early 1970’s.

p.s. Our book    EducationAisle Sentence Correction Nirvana    discusses  these concepts of comparison , their application and examples in significant detail. If someone is interested, PM me your email-id; I can mail the corresponding section.

NunuBot · Answer

I need some clarification for the usage of  Higher Than  in sentence correction questions.

In OG 2019, answer for 758 states this:
  Correct  : Prices are higher now than (those of a year ago) ...
  Incorrect  : Prices are higher now than (a year ago)
 Reason : "The sentence as written makes an illogical comparison between prices at the producer level and a time period (a year ago); surely the intended comparison is between such prices now and those of a year ago" - Direct quote from OG

But in OG 2019, answer for 772 states this:
  Correct  : Prices are expected to be higher this year than (last) ...
  Incorrect  : Prices are expected to be higher this year than (last year's)
 Reason : "the possessive  year's  is not parallel with the adverbial phrase  this year " - Direct quote from OG

Focusing specifically on the usage of "higher than" and ignoring all the other errors in the options provided (eg. not parallel),  when is it right to compare (prices vs last) and (prices vs that of last year)?  I've copied the questions below for your easy reference.

ps: I dont need a breakdown on how you derive the answer - that is available on another existing thread in this forum. Also, i have the view that the objects of comparison should have higher priority than the sentence being parallel, so i would like to exclude parallelism from the discussion for now if possible.

758. Prices at the producer level are only 1.3 percent higher now  than a year ago and are going down, even though floods in the Midwest and drought in the South are hurting crops and therefore raised  corn and soybean prices.

(A) than a year ago and are going down, even though floods in the Midwest and drought in the South are hurting crops and therefore raised

(B) than those of a year ago and are going down, even though floods in the Midwest and drought in the South are hurting crops and therefore raising

(C) than a year ago and are going down, despite floods in the Midwest and drought in the South, and are hurting crops and therefore raising

(D) as those of a year ago and are going down, even though floods in the Midwest and drought in the South hurt crops and therefore raise

(E) as they were a year ago and are going down, despite floods in the Midwest and drought in the South, and are hurting crops and therefore raising

772.  Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were  last year.

(A) Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were

(B) Heating-oil prices are expected to rise higher this year over last because refiners pay about $5 a barrel for crude oil more than they did

(C) Expectations are for heating-oil prices to be higher this year than last year's because refiners are paying about $5 a barrel for crude oil more than they did

(D) It is the expectation that heating-oil prices will be higher for this year over last because refiners are paying about $5 a barrel more for crude oil now than what they were
 
(E) It is expected that heating-oil prices will rise higher this year than last year's because refiners pay about $5 a barrel for crude oil more than they did

EducationAisle · Answer

Hi  NunuBot , am pretty sure that  Prices are higher now than a year ago  is a correct statement. For that reason, we should consume  official  explanations   with a  pinch of salt :).

NunuBot · Answer

Thanks for the replies.

I am under the impression that: 
...  higher A than B  ....

Would require both A and B to be comparable and parallel, with being comparable more important than being parallel.

So...
  Correct  : Market prices are expected to be higher (now) than (a year ago)
  Correct  : Market is expected to charge a higher (price now) than (those a year ago)

Since (now) and (a year ago) are comparable, and so is (prices now) and (those a year ago).

By the same token:
  Incorrect  : Market is expected to charge a higher (price now) than (a year ago)
  Incorrect  : Market is expected to charge a higher (price now) than (last year's)

Given the inconsistencies in the OG's answers on the usage of  Higher Than  across multiple questions, perhaps I should not rely on this phrase for the initial split.

EducationAisle · Answer

Well, this is incorrect for  another  reason.

When a sentence uses an  action  verb ( charge  in this case) and there is a  tense change  between the two parts of comparison sentence, then it becomes  mandatory  to  explicitly  mention the verb with the  correct  tense. So, the correct sentence will be:

Market is expected to charge a higher price now than it did a year ago.

Or

Market is expected to charge a higher price now than it charged a year ago.

This can be eliminated because of  parallelism ; there is nothing parallel to  last year's  in the first half of the sentence.

heyrohit · Answer

I've my official exam in 3 days and I am still struggling with comparisons.

Can someone help me with how to figure out when is verb required vs not in following comparisons

1. Prices are five percent higher now than a year ago.

My understanding:
What is being compared? - Prices now vs Prices a year ago so it should be
 Prices  are five percent higher now  those  of a year ago.

2. Heating-oil prices are expected to be higher this year than last
What is being compared? - Prices this year vs Prices last year
Above is correct. I don't understand why following is wrong
 Heating-Oil prices are expected to be higher this year and last's (or prices of last year)

I've found myself often struggling with more than, more   than related questions.

Is there any article which I can use?

Thank you

EducationAisle · Answer

H Rohit, both the following sentences are correct:

1. Prices are five percent higher now than a year ago.

2. Heating-oil prices are expected to be higher this year than last

This is not a great construct, more from a  parallelism  perspective. When we have possessive (such as  last's  in this case), one would expect a similar construct on the left hand side. For example:

Peter's salary is more than Michael's.

hwcs · Answer

Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were  last year.

In the aforementioned question, the comparison "higher this year than last" is considered grammatically correct. However, in the following question, a similar comparison is labeled as incorrect. Am I missed something?

Prices at the producer level are only 1.3 percent higher now  than a year ago and are going down, even though floods in the Midwest and drought in the south are hurting crops and therefore raised  corn and soybean prices.

lovikansal · Answer

Thank you for asking this question. I think your question is related to Ellipsis, one of the most complicated topics for me. But, I will try to answer.

Firstly, let's consider the sentence: Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were last year.:

In this sentence ellipsis is used at 'than last'. It means, than last year's heating-oil prices.

Now, let's consider the second sentence: Prices at the producer level are only 1.3 percent higher now than a year ago and are going down, even though floods in the Midwest and drought in the south are hurting crops and therefore raised corn and soybean prices.:

In this sentence ellipsis should be used at 'than a year ago'. However, when we try to replace the omitted part of the sentence, we either get:
1. than a year ago's prices at the producer level, which is grammatically incorrect as ago's is not a word. We can only use a possessive noun in such situations, for eg: Last year's prices.

2. If we omit the verb: than prices at the producer level a year ago, which is also grammatically incorrect as there should have been a verb here. Correct form: than prices at the producer level were a year ago.

If we keep the verb: than prices at the producer level are a year ago, which is also grammatically incorrect as there should have been a past tense verb here. Correct form: than prices at the producer level were a year ago.

Hopefully, this helped you.

Bunuel · Answer

The first question is discussed in detail  HERE .

The second question is discussed in detail  HERE .

Hope it helps.

P.S. I also merged this discussion with the older one on the same topic.

hwcs · Answer

Thanks! This definitely helps.

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