SELF-STUDY

Parallelism

Parallelism in writing refers to the presentation of equivalent (parallel) ideas in equivalent (parallel) grammatical form.

One way you can quickly improve your scientific writing is to be conscious of parallelism in pairs or lists of items in a sentence and to construct them so that they are grammatically parallel.

Consider the following two sentences:

(a) The patient complained of fatigue, headaches, and said that he had no appetite.
(b) The patient complained of fatigue, headaches, and loss of appetite.

Sentence (a) suffers from nonparallelism: the 3 equivalent ideas (ie, the symptoms) are not presented in equivalent grammatical form but as 2 direct object nouns (fatigue and headaches) and 1 indirect statement (said that he had no appetite).

Sentence (b) illustrates parallelism in writing: the 3 equivalent ideas are presented in equivalent grammatical form as 3 direct object nouns (fatigue, headaches, loss of appetite).

Most readers would agree that the parallel structure of sentence (b) makes it the smoother and more efficient of the 2 sentences to read.

Here are some other typical examples of sentences with faulty parallel structure:

not only ... but also

This complex disease has been identified as a high cost driver not only for ICUs but also from the perspective of hospitals and society.

Because not only and but also form a pair, the items after each should be parallel in form. Therefore, revise so that for follows each:

This complex disease has been identified as a high cost driver not only for ICUs but also for hospitals and society.

either ... or

Pregnant rats were exposed to either 2 g or kept at 1 g.

Because either and or form a pair, the items after each should be parallel in form. Therefore, revise so that a past participle follows each:

Pregnant rats were either exposed to 2 g or kept at 1 g.

both ... and

Patients’ mental health status was assessed both at intake and discharge.

Because both and and form a pair, the items after each should be parallel in form. Therefore, revise so that at follows each:

Patients’ mental health status was assessed both at intake and at discharge.

Or, revise by moving at before the both ... and construction, so that a noun follows each:

Patients’ mental health status was assessed at both intake and discharge.

than

X was more strongly downregulated in the transgenic mice than wildtype mice.

The pair of compared items before and after than should be parallel in form. Therefore, revise to:

X was more strongly downregulated in the transgenic mice than in the wildtype mice.

YOU TRY!

Revise the following sentences so that parallel items are written in parallel grammatical form.

1.: Mice were treated either with vehicle or nontoxic dose of stampidine.

2.: For mild forms of bacterial or fungi folliculitis, over-the-counter drugs may be prescribed.

3.: X and Y mRNA were also detected both in the organ of Corti and the spiral ganglion.

4.: Smith et al concluded that a decentered decorative lens causes not only poor cosmetic appearance but also reduces the optical quality of the eye [4].

5.: The number of fibers generated in the optic nerve injected with X was similar to that in the optic nerve with an injection of 100 µM Y.

6.: Postoperative SE was lower in the stable refractive group than the unstable refractive group.

7.: Aldose reductase is the major contributor to diabetes-induced oxidative stress in lens, kidney, and the nerve.

8.: In the X group, treatment with Y resulted in decreased CRT, but did not increase the BCVA.

9.: Recent advances in enhanced-depth imaging and high-penetration OCT have enabled visualization of the sclera and the choroid thickness can be measured immediately.

10.: In in vitro models, the effects of hemodilution, ischemia-perfusion, and new cells being recruited were not factored in [8-12].

11.: Several explanations are possible for why the stereoacuity obtained with the X test was better than that of the Y test.

12.: Polygenetic variation alters the behaviors of a biological pathway in response to environmental exposures including allergens (bacterial and virus), tobacco smoke, and ambient and indoor air pollution.

13.: Distinctly stronger immunostaining of X was observed in the airway cells of the repeatedly antigen-challenged mice than those of the sensitized control mice.

14.: On examination, he was pale and with mild pyrexia.

ANSWERS

1.: Mice were treated either with vehicle or with nontoxic dose of stampidine.; The items after the paired construction (either ... or) are now written in grammatically parallel form (ie, prepositional phrases beginning with ‘with’). The following revision is also possible:; Mice were treated with either vehicle or nontoxic dose of stampidine.; By moving ‘with,’ we have revised the sentence so that the items after ‘either ... or’ are grammatically parallel (ie, nouns/noun phrases: vehicle, nontoxic dose).

2.: For mild forms of bacterial or fungal folliculitis, over-the-counter drugs may be prescribed.; The pair of words modifying ‘folliculitis’ are now written in grammatically parallel form (ie, adjectives: bacterial, fungal).

3.: X and Y mRNA were also detected both in the organ of Corti and in the spiral ganglion.; The items after the paired construction ‘both ... and’ are now written in grammatically parallel form (ie, prepositional noun phrases beginning with ‘in’). The following revision is also possible:; X and Y mRNA were also detected in both the organ of Corti and the spiral ganglion.; By moving ‘in,’ we have revised the sentence so that the items after ‘both … and’ are grammatically parallel (ie, noun phrases: the organ of Corti, the spiral ganglion).

4.: Smith et al concluded that a decentered decorative lens not only causes poor cosmetic appearance but also reduces the optical quality of the eye [4].; The items after the paired construction ‘not only … but also’ are now written in grammatically parallel form (ie, 3rd-person singular, simple present verb: causes, reduces).

5.: The number of fibers generated in the optic nerve injected with X was similar to that in the optic nerve injected with 100 µM Y.; The pair of compared items before and after ‘than’ are now written in grammatically parallel form (ie, with past participle modifiers: injected with).

6.: Postoperative SE was lower in the stable refractive group than in the unstable refractive group.; The pair of compared items before and after ‘than’ are now written in grammatically parallel form (ie, prepositional phrases beginning with ‘in’).

7.: Aldose reductase is the major contributor to diabetes-induced oxidative stress in the lens, kidney, and nerve.; The 3 items in the list are now written in grammatically parallel form (ie, nouns. all 3 of which are governed by ‘the’).

8.: In the X group, treatment with Y resulted in decreased CRT, but not in increased BCVA.; The sentence has been improved so that the 2 findings are written in grammatically parallel form (ie, as objects of ‘resulted in,’ each with preceding past participle modifiers: decreased CRT, increased BCVA.)

9.: Recent advances in enhanced-depth imaging and high-penetration OCT have enabled visualization of the sclera and immediate measurement of the choroid thickness.; The sentence has been improved so that the 2 direct objects of the verb are written in grammatically parallel form (ie, 2 noun phrases: visualization of, immediate measurement of).

10.: In in vitro models, the effects of hemodilution, ischemia-perfusion, and recruitment of new cells were not factored in [8-12].; The 3 items in the list are now written in grammatically parallel form (ie, noun phrases: hemodilution, ischemia-perfusion, recruitment of new cells).

11.: Several explanations are possible for why the stereoacuity obtained with the X test was better than that obtained with the Y test.; The pair of compared items before and after ‘than’ are now written in grammatically parallel form (ie, modifying past participle: obtained with). The following revision is also possible:; Several explanations are possible for why the stereoacuity of the X test was better than that of the Y test.; The pair of compared items before and after ‘than’ are now written in a different parallel form (ie, preposition: of). (However, the first revised version is preferable, given the use of a verb, ‘obtained,’ rather than of a preposition. —See the ‘Energize your writing with strong and active VERBS’ module.)

12.: Polygenetic variation alters the behaviors of a biological pathway in response to environmental exposures including allergens (bacterial and viral), tobacco smoke, and ambient and indoor air pollution.; The pair of items (in parentheses) modifying ‘allergens’ are now written in grammatically parallel form (ie, adjectives: bacterial, viral).

13.: Distinctly stronger immunostaining of X was observed in the airway cells of the repeatedly antigen-challenged mice than in those of the sensitized control mice.; The pair of compared items before and after ‘than’ are now written in grammatically parallel form (prepositional noun phrase beginning with ‘in’).

14.: On examination, he was pale and mildly pyrexic.; The sentence has been improved so that the 2 presenting signs of illness are written in grammatically parallel form (ie, adjectives: pale, pyrexic).