In a review of 2000 studies of human behavior that date back

Question

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss  psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,  none could be taken seriously.

(A) psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,

(B) psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and

(C) psychologists declared that since most of the studies, having failed to control for such variables as social class and family size,

(D) psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,

(E) psychologists declared that since most of the studies had failed to control for variables such as social class and family size,

The Official Guide for GMAT Review, 13th Edition, 2012

Practice Question  
Question No.: SC 1

daagh · Accepted Answer

The core point here is that the psychologists declared about something that had happened earlier. So the act of declaration requires a simple past such as declared and the earlier event failing requires a past perfect such as had filed.

A. psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,----- lacks a working verb for the subject psychologists. So a fragment

B psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and
In this case Modifier error still stands.

C psychologists declared that since most of the studies, having failed to control for such variables as social class and family size, ---- The subordinate clause introduced by since lacks a verb and hence a fragment

D. psychologists declared that since most of the studies fail in controlling for such variables like social class and family size, ------- shift of tense using a present tense verb fail is wrong; as also, use of like is wrong.

E psychologists declared that since most of the studies had failed to control for variables such as social class and family size, ------- correct choice with proper sequence of tense and use of such as to mark examples.

USADream · Answer

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could be taken seriously.

A psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,
B psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and
C psychologists declared that since most of the studies, having failed to control for such variables as social class and family size,
D psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,
E psychologists declared that since most of the studies had failed to control for variables such as social class and family size,

POE:
1. Subject psychologists needs a main verb and gerund (declaring)cannot be a main verb.so use of verb declared is correct.
so A & B is out.
2.In choice C: having failed is a participial form and as such cannot be the main verb in the clause.also it looks very awkward.so choice is also out.
3.In choice D: English has a rule of sequence of tenses:
once a verb form is marked for past tense,the following verb forms that describe the same object or event have to be in the past tense as well. Thus,fail is the wrong verb form. The expression such X like Y is incorrect in English; the correct usage is such X as Y.
by this reason D is also out.

so we are left with correct choice E.
however one can argue why past perfect is used in choice E?where are the sequence of event? and this may confuse some one whether this is the correct choice!!
here is explanation for past perfect "had failed" is correctly used:

All the events in the statement:

1. Psychologists declared
2. Studies failed
3. Could not be taken seriously

Are all of these three events independent?

The answer is No.

The first event i.e. declaration is independent because the act of declaring is not dependent on what was declared.

However, the failure of studies and taking them seriously are dependent. The failure of studies to control for variables must precede the event - they cannot be taken seriously. Isn’t it?

Can we say that both the second and the third events take place simultaneously? It means saying that studies failed to control for variables and at the same time, they could not be taken seriously.

No. The second event must precede third event. Why? The reason is that the second event explains the third event. First, the studies failed. And because it failed, it could not be taken seriously.

So to express this sequence that first the studies failed and then they could be taken seriously, past perfect tense is used for the event that took place earlier.

kudos if you like!!

ExpertsGlobal5 · Answer

Dear Friends,

Here is a detailed explanation to this question -

Meaning is crucial to solving this problem: 
Understanding the intended meaning is key to solving this question; the intended core meaning of this sentence is that two Swiss psychologists declared that since most of the studies had failed to control for variables such as social class and family size, none could be taken seriously.

Concepts tested here: Meaning + Verb Forms + Tenses + Grammatical Construction + Idioms

• If a sentence contains multiple past actions, the past perfect tense (marked by the use of the helping verb “had”) is used to refer to all but the most recent action; the simple past tense is used to refer to the most recent action.
• The simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature.
• “like” is used for comparing nouns, “as” is used for comparing actions/clauses, and “such as” is used for giving examples.
• For referring to the purpose/intent of actions the infinitive verb form ("to + base or of verb") is preferred over the present participle ("verb+ing").

A:  This answer choice fails to form a complete sentence; as "declaring" is a present participle ("verb+ing") acting as a noun modifier, there is no active verb to act upon the subject "psychologists".

B:  This answer choice fails to form a complete sentence; as "declaring" is a present participle ("verb+ing") acting as a noun modifier, there is no active verb to act upon the subject "psychologists". Further, Option B alters the meaning of the sentence through the phrases "that most of the studies failed" and "and none could be taken seriously"; the omission of any coordinating conjunctions (such as "since" in the correct answer choice) incorrectly implies that most of the studies had failed to control for variables such as social class and family size, and   as a separate action  , none could be taken seriously; the intended meaning is that most of the studies had failed to control for variables such as social class and family size, and   as a result  , none could be taken seriously. Additionally, Option B incorrectly uses the simple past tense verb "failed" to refer to the earliest of multiple actions that concluded in the past - most of the studies failing to control for certain variables, none of the studies being able to be taken seriously, and the Swiss psychologists declaring this information; please remember, if a sentence contains multiple past actions, the past perfect tense (marked by the use of the helping verb “had”) is used to refer to all but the most recent action; the simple past tense is used to refer to the most recent action. Moreover, Option B incorrectly uses "like" to provide the examples of "social class" and "family size"; please remember, “like” is used for comparing nouns, “as” is used for comparing actions/clauses, and “such as” is used for giving examples. Besides, Option B uses the present participle ("verb+ing" - "controlling" in this sentence) to refer to the intent behind the action "failed"; please remember, for referring to the purpose/intent of actions the infinitive verb form ("to + base or of verb") is preferred over the present participle ("verb+ing" - "controlling" in this sentence).

C:  This answer choice fails to form a complete sentence; as "having failed" is a present participle phrase ("verb+ing") acting as a noun modifier, there is no active verb to act upon the subject "most of the studies". Further, Option C incorrectly places information vital to the meaning of the sentence - the fact that most of the studies failed to control for such variables as social class and family size - between commas; please remember, information vital to the meaning of the sentence cannot be placed between commas.

D:  This answer choice incorrectly uses the simple present tense verb "fail" to refer to the earliest of multiple actions that concluded in the past - most of the studies failing to control for certain variables, none of the studies being able to be taken seriously, and the Swiss psychologists declaring this information; please remember, if a sentence contains multiple past actions, the past perfect tense (marked by the use of the helping verb “had”) is used to refer to all but the most recent action; the simple past tense is used to refer to the most recent action, and the simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature. Additionally, Option D incorrectly uses "like" to provide the examples of "social class" and "family size"; please remember, “like” is used for comparing nouns, “as” is used for comparing actions/clauses, and “such as” is used for giving examples. Besides, Option D uses the present participle ("verb+ing" - "controlling" in this sentence) to refer to the intent behind the action "failed"; please remember, for referring to the purpose/intent of actions the infinitive verb form ("to + base or of verb") is preferred over the present participle ("verb+ing" - "controlling" in this sentence).

E:   Correct.  This answer choice acts upon the subjects "psychologists" and "most of the studies" with the active verbs "declared" and "had failed" respectively to form complete thoughts, leading to complete sentences. Moreover, Option E uses the phrase "that since most of the studies"; the use of the coordinating conjunction "since" conveys the intended meaning - that most of the studies had failed to control for variables such as social class and family size, and   as a result  , none could be taken seriously. Further, Option E correctly use the past perfect tense verb "had failed" to refer to the earliest of multiple actions that concluded in the past - most of the studies failing to control for certain variables, none of the studies being able to be taken seriously, and the Swiss psychologists declaring this information. Additionally, Option E correctly uses "such as" to provide the examples of "social class" and "family size. Option E also avoids the grammatical construction error seen in Option C, as it places no information between commas. Besides, Option E uses the infinitive verb form ("to + base form of verb" - "to + control") to refer to the intent behind the action "had failed".

Hence, E is the best answer choice.

To understand the concept of "Simple Tenses" on GMAT, you may want to watch the following video (~1 minute):

https://www.youtube.com/watch?v=eZj-SubJwsM

To understand the concept of using "Infinitive Verb Forms" and "Present Participles" on GMAT, you may want to watch the following video (~2 minutes):

https://www.youtube.com/watch?v=tKizVOYx0_k

To understand the concept of "Past Perfect Tense" on GMAT, you may want to watch the following video (~2 minutes):

https://www.youtube.com/watch?v=eFGxC37OOGU

All the best!
Experts' Global Team

WaterFlowsUp · Answer

A psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,---- Declaring does not represent the correct verb tense
B psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and---- Declaring does not represent the correct verb tense
C psychologists declared that since most of the studies, having failed to control for such variables as social class and family size, -having failed is again wrong
D psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,----declared is simple past which is not incorrect but a past perfect is just what we need
E psychologists declared that since most of the studies had failed to control for variables such as social class and family size,---bingo

dentobizz · Answer

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss  psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size , none could be taken seriously.

A] psychologists,  declaring that since most of the studies had failed to control for such variables as social class and family size ,-->NO main verb
B] psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and
C] psychologists declared that since most of the studies, having failed to control for such variables as social class and family size, 
D] psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,
E] psychologists  declared  that since most of the studies had failed to control for variables such as social class and family size,-->verb and modifier are correct

HTH

egmat · Answer

https://gmatclub.com/blog/wp-content/uploads/2013/07/gmat2-banner11-e1373945998281.jpg Hi Solanki, Wish you and you family a very Happy and Prosperous Diwali. Thanks for posting your doubt here. :-)

Let's analyze Choice A first: psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size: In this answer choice, "declaring", the verb-ing modifier modifies "two Swiss psychologists. However, the main subject of the sentence, "two Swiss psychologists" does not have a main verb. Note that the subject of the verb "had failed" is "most of the studies" and the subject for "could be taken" is "none". So we have fragment error here. Now let's take a look at Choice E : psychologists declared that since most of the studies had failed to control for variables such as social class and family size,: The first thing that you need to see here is that "declared" is NOT a verb-ed modifier. It is the VERB for the subject "two Swiss psychologists". It is so because the psychologists themselves are the doer of the action of declaring. The error of missing verb has been rectified in this choice. For more on whether a verb-ed word is a past tense verb or a verb-ed modifier, please read the following article: ed-forms-verbs-or-modifiers-134691.html Hope this helps. :-)

Thanks. Shraddha

GMATPill · Answer

We have posted a video solution to this question here: https://www.gmatpill.com/official-guide- ... p?id=ogsc1

Notice this question partially tests "such as" vs "like"

When you are listing out examples, you should use "such as"...

farhanchaudhary · Answer

Meaning After reviewing 2000 studies on human behavior swiss psychologists declared something. This declaration stated that most of the studies didn't take into account variables such as class and family size. Due to this discrepancy in studies, none of the studies could be taken seriously Error Analysis In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could be taken seriously. The original statement has 2 major errors. Modifier Error: The modifier declaring is placed after swiss psychologists and before the close. It is ambiguous what is "declaring" modifying in the statement. The correct answer choice should change this modifier to verb-ed modifier or remove ambiguity Usage of As: "Such Variables" are compared to social class and family size. When as is used for comparison it is used along with a clause. " Variable were biased as they were inconclusive" . In this sentence the correct usage of as would be to present examples, hence we need to use such as. POE A psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, For the original errors mentioned in error analysis B psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and In this case Modifier error still stands. Also as is replaced by like. Like can be used for comparison between 2 entities, hence usage of like is wrong here C psychologists declared that since most of the studies, having failed to control for such variables as social class and family size, Although the sentence corrects the original modifier error it introduces the modifier having failed to control which creates ambiguity in the sentence. Modifier placed after a clause modifier the entire clause. Hence, in this cases the declaration of psychologist is modified by having. As error still stands D psychologists declared that since most of the studies fail in controlling for such variables like social class and family size, Correct the modifier error but introduces like which is incorrect form of comparison E psychologists declared that since most of the studies had failed to control for variables such as social class and family size, This statement is correct as it corrects the modifier error and also introduces social class and family size as example This is the e-gmat way

. Do weigh in experts.

EducationAisle · Answer

I don't believe there is any ambiguity.  declaring  is modifying  two Swiss psychologists .

The sentence does use  such variables as . This construct is also valid, when the intent is to give  examples . There are quite a few examples of this nature in the OG. For example: #64, OG-13:  Doctors generally agree that such factors as cigarette smoking, eating rich foods high in fats, and alcohol consumption ....

A major issue with this option is that with this option, the original sentence is  not  a sentence at all. It is just a  fragment , because there is no main  verb . Please note that  declaring  should be changed to  declared . However, this  declared  is  not  (what you have called) a  verb-ed modifier . It is actually a  verb  (a simple past tense verb).

Again, there is no  ambiguity  with respect to modifier. The issue is same as it is in option A: It is just a  fragment .

The major issue is that  since  is used as a  subordinating conjunction  here, and so, must be followed by a  clause . But,  most of the studies, having failed to control for such variables as social class and family size  is not a clause.

This option is better than the above options, in the sense that this is at least a  sentence . An issue is with  tense , since this uses  simple present  tense ( fail ) to depict an event that happened in past. Also, as you have rightly pointed out,  like  is incorrect.

Hope it helped. Please note that  before  we start applying the myriad  micro  rules (modifier error, pronoun ambiguity, subject verb agreement etc. etc.), please make sure that you apply the  macro  rule: Is the option resulting in a  sentence  at all!

p.s. Our book   SC Nirvana   discusses " Clauses ", their application and examples in significant detail. If you can PM you email, I can send you the corresponding section.

him1985 · Answer

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists,  declaring that since most of the studies had failed to control for such variables as social class and family size,  none could be taken seriously.

A psychologists,  declaring  that since most of the studies had failed to control for such variables as social class and family size,
B psychologists,  declaring  that most of the studies  failed  in not controlling for such variables like social class and family size, and
C psychologists declared that since most of the studies,  having failed  to control for such variables as social class and family size, 
D psychologists declared that since most of the studies  fail  in controlling for such variables like social class and family size,
E  psychologists declared that since most of the studies had failed to control for variables such as social class and family size,

Verb Sequencing.

chetan2u · Answer

Hi,
the Q tests on following aspect:-
 1) Verb +ing modifier-- 
by converting the portion after psychologists in verb+ing modifier, we have the noun psycho without a verb/action
eliminate A and B...
 2) use of Such as-- 
we use such as to show examples..
D can be eliminated
3) In C  having clause  does not make sense..
 4) Use of Past perfect-- 
Since we are talking of studies of an earlier period, past perfect is correctly used in E..
ans E

TeamGMATIFY · Answer

In a review of 2,000 studies of human behavior that date back to the 1940s, two Swiss  psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size , none could be taken seriously.

(A) psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,
 Verb+ing (declaring) does not act as a verb. Hence this statement lacks a main verb 
(B) psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and
 Verb+ing (declaring) does not act as a verb. Hence this statement lacks a main verb 
(C) psychologists declared that since most of the studies, having failed to control for such variables as social class and family size,
 Having does not makes sense. Since the study happened in the past, hence perfect tense is needed. 
(D) psychologists declared that since most of the studies fail in controlling for such variables like social class and family size, 
 Such as is used to state examples, not like 
(E) psychologists declared that since most of the studies had failed to control for variables such as social class and family size,
 Correct. Since the study happened in the past, hence perfect tense is needed.

EducationAisle · Answer

Since  (used in the sense of  because  here) is used as a  subordinating conjunction  in this sentence.

Subordinating conjunctions  mark the start of a Dependent  clause . In other words, a  clause  (portion of sentence with a  verb ) must follow  since . Here, the portion of sentence that follows  since  is:

most of the studies, having failed to control for such variables as social class and family size

This does  not  have a verb. Hence, this portion is  not  a clause.

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

WiziusCareers1 · Answer

There are two actions in this sentence - 'declaring something' and 'failed to control'. Whenever you see more than 1 action, try to get them straight in time. 
what happened first? The studies failed to control.....
So, this part takes  "had"  and the other part  "declaring"  must be in the past tense. 
The only answer choice that corrects both the errors is E.

A)  'declaring' should be 'declared' 
B)  'declaring' should be 'declared' 
C)  'having failed' should be 'had failed' 
D)  'fail' should be 'had failed' 
E)  correct 
 
Highlighted only the decision points for a faster understanding.

GMATmantra · Answer

If we scan first few words we can see a split between ‘psychologists, declaring…’ and ‘psychologist declared….’
Here ‘psychologist’ is the subject. In A and B, we should have verb after second comma. In A, we have ‘none could..’ after second comma. Verb is missing. Eliminate.
Similarly in B, ‘and’ is present after second comma. Verb is missing. Eliminate B
If we compare last words of C, D and E, we have split between ‘such as’ and such like’. In D, ‘such like’ is wrong in GMAT. Eliminate D.

In C, ‘declare that..’ must followed with a clause. Subject is ‘most of the …’, after that we have two commas, verb must be present after second comma. We have ‘none..’ after second comma. Verb is missing after second comma. Eliminate C.

Hence E is the correct answer.

sasyaharry · Answer

We can easily find the answer using a timeline

ydmuley · Answer

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could be taken seriously.

(A) psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,

(B) psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and

(C) psychologists declared that since most of the studies, having failed to control for such variables as social class and family size,

(D) psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,

(E) psychologists declared that since most of the studies had failed to control for variables such as social class and family size,

The Official Guide for GMAT Review, 13th Edition, 2012

Practice Question
Question No.: SC 1

Show Answer

Official Answer

E

HimanshuW11 · Answer

In a review of 2,000 studies of human behavior that date back to the 1940s, two Swiss  psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,  none could be taken seriously.

(A) psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,

"Declaring" is a gerund and not the verb of the sentence hence it is a fragment and goes out.

(B) psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and

"Declaring" is a gerund and not the verb of the sentence hence it is a fragment.
Such...like is used to compare things hence not the right usage here. Like is the right usage.

(C) psychologists declared that since most of the studies, having failed to control for such variables as social class and family size,
having failed is the participle form and not the main verb of the sentence, hence it goes out.

(D) psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,
FAIL is not the right verb for the past tense reporting verb "declared".
like is not the appropriate usage.

(E) psychologists declared that since most of the studies had failed to control for variables such as social class and family size,
Right usage of the tense, verb

EMPOWERgmatVerbal · Answer

Hello Everyone!

Let's take a closer look at this question to find the correct answer! Before we dive in, here is the original question, with any major differences between each option highlighted in  orange :

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss  psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,  none could be taken seriously.

(A) psychologists , declaring  that since most of the studies  had failed  to control for such variables as social class and family size,
(B) psychologists , declaring  that most of the studies  failed  in not controlling for such variables like social class and family size, and
(C) psychologists  declared  that since most of the studies,  having failed  to control for such variables as social class and family size, 
(D) psychologists  declared  that since most of the studies  fail  in controlling for such variables like social class and family size,
(E) psychologists  declared  that since most of the studies  had failed  to control for variables such as social class and family size,

After a quick scan over the options, it's clear that two major issues need to be addressed:

1. declaring vs. declared
2. had failed / failed / having failed / fail

Let's start with #1 on our list: declaring vs. declared. No matter which one we choose, it will knock out 2-3 options quickly.

We know that we have a past tense verb ( declared ) and a present participle ( declaring ).

We can also see that the answers that use "declaring" also have a comma before them, creating a non-essential clause. That means whatever we put between commas is not important, and can be removed without changing the meaning or grammatical correctness of what's left over. Non-essential clauses are a popular problem with GMAT SC questions, so we'll check to make sure they're being used correctly while also checking for verb tense issues.

To make this a little easier to see, I've added the non-underlined portions of the sentence:

(A) In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists,  declaring that since most of the studies had failed to control for such variables as social class and family size , none could be taken seriously. -->  WRONG

If we remove the non-essential clause that begins with "declaring," we see that the remainder of the sentence doesn't make sense because it's missing a verb (What did the psychologists  do ?). It also doesn't make sense to use the present participle here. The psychologists are not still declaring the studies are screwed up - it all happened in the past. Therefore, this cannot be the correct option.

(B) In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists,  declaring that most of the studies failed in not controlling for such variables like social class and family size , and none could be taken seriously. -->  WRONG

Again, if we remove the non-essential clause that begins with "declaring," we see that the remainder of the sentence doesn't make sense because it's missing a verb (What did the psychologists  do ?). It also doesn't make sense to use the present participle here. The psychologists are not still declaring the studies are screwed up - it all happened in the past. Therefore, this cannot be the correct option.

(C) In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists  declared  that since most of the studies,  having failed to control for such variables as social class and family size , none could be taken seriously. -->  WRONG

Okay, so while this sentence uses the correct past tense verb tense "declared," there is still a problem with non-essential clauses. If we cross out the phrase, "having failed to control for such variables as social class and family size," what we're left with doesn't make sense. Therefore this also cannot be a correct option.

(D) In a review of 2000 studies of human behavior that date back to the 1940's,  two Swiss psychologists declared  that since most of the studies fail in controlling for such variables like social class and family size, none could be taken seriously. -->  GOOD

There is no issue with how the verb "declared" is handled here, so let's save it for later!
 
(E) In a review of 2000 studies of human behavior that date back to the 1940's,  two Swiss psychologists declared  that since most of the studies had failed to control for variables such as social class and family size, none could be taken seriously. -->  GOOD

There is no issue with how the verb "declared" is handled here, so let's save it for later!
 
 You can eliminate options A, B, and C because they either use the wrong verb tense or the commas around the non-essential clauses are misplaced!

Now that we've narrowed it down to only 2 options,  let's tackle #2 on our list: fail vs. had failed.

We know that the psychologists declared in the past that the studies shouldn't be taken seriously. We also know that  before they made that declaration , the studies had failed in some way. This means we have two past tense events to deal with! We also know that we should use different verbs to indicate what order these events happened in:

Past Perfect --> Past Tense --> Present --> Future

Let's see how each answer stacks up!

(D) psychologists declared that since most of the studies  fail  in controlling for such variables like social class and family size,

This is  INCORRECT  because it uses the present tense "fail," which conveys the wrong meaning. These studies aren't still failing - they failed in the past, causing two Swiss psychologists to declare them bad studies.

(E) psychologists declared that since most of the studies  had failed  to control for variables such as social class and family size,

This is  CORRECT ! It uses the past perfect "had failed" to show that the studies had failed  before  the psychologists declared them bad studies.

There you have it - option E is the correct choice!  It uses the correct verb forms, and doesn't have any problems with punctuation or non-essential clauses!

Don't study for the GMAT. Train for it.

In a review of 2000 studies of human behavior that date back

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In a review of 2000 studies of human behavior that date back

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards