Nouns locked in verbs (nominalizations)
Consider the following sentence:
(a) A comparison was made of the effects of pH vs temperature.
Note how the most important action, to compare, is frozen in the abstract noun comparison. Such nouns are called nominalizations, and excessive nominalization typifies academic and bureaucratic writing. To tell a simpler and clearer story, one that is less abstract, we would use the most important action in the sentence as the verb. In transitive active voice, the sentence would become
(b) We compared the effects of pH vs temperature.
And in transitive passive voice, the sentence would be
(c) The effects of pH and temperature were compared.
You might select (a) if you were trying to impress the reader (to a reader who did not know better, a comparison was made might sound more important than we compared) or if you wanted to increase the length of your paper but lacked additional information or ideas (students learn and love the academic style because it helps them inflate three pages of ideas into a five-page essay). Regarding the latter point, note that sentence (a) uses 11 words while sentences (b) and (c) use only 8. Also note that (b) and (c) but especially (b) tell a simple story that is easy to understand and that anyone who would write (a) would probably also use the other characteristics of the academic style. Also note that while (b) and (c) use the same number of words, the actor is described in (b) but not in (c).
To write clearly, scientists should avoid needless nominalizations. In other words, scientists should not be needlessly abstract and should usually express the important action in the verb.
But some nominalizations are necessary or useful. Consider the following sentence:
Fragmentation, grazing, forestry, and nutrient deposition are decreasing the biological diversity of many of the earth's remaining semi-natural ecosystems.
Of the four subjects, fragmentation and nutrient deposition are the most obvious examples of nominalizations. But converting these abstract ideas into verbs while maintaining this sentence would be very difficult. Moreover, the main action in the sentence is not really fragmentation and deposition but decreasing. Finally, most readers of this paper would be familiar with the terms fragmentation, grazing, forestry, and nutrient deposition and would understand that the writer is using these abstractions as characters in a story. Some characters are reducing biodiversity. Which characters? Fragmentation, grazing, forestry, and nutrient deposition. In this example, the abstractions (the nominalizations) enable the writer to tell a story that would be much too long and complex if he or she expanded the nominalizations into verbs and clauses.
So, use nominalizations sparingly. Do not use a nominalization until you have determined that expressing the nominalization as a verb will not improve the sentence.