Compare and Contrast the Use of Active and Passive Voice
| x | Active | Passive |
| Problem | Can put too much emphasis on the agent/action doer. (Is who did it important? Should this information be up front in the sentence? Should it even be mentioned at all?) | Can become too wordy (requires prep phrases) or ambiguous. |
| Examples |
Better: Two model simulations (Figures 1 and 2) illustrate how zones of fracture concentration influence groundwater flow. These simulations show. . . . |
Poor: Groundwater flow is influenced by zones of fracture concentration, as can be recognized by the two model simulations (see Figures 1 and 2), by which one can see . . . . |
| General Principle | Put concrete nouns that can do something in front of active verbs. |
1. Write direct sentences that have simple subjects and verbs. Not—Easy comparison of the samples was allowed by the taking of photomicrographs. Instead—Photomicrographs were taken to allow easy comparison of the samples. 2. Choose the passive when you don't know who did it, your readers don't care who did it, or you don't want them to know who did it. |
| x | Active | Passive |
| Context |
Use in topic sentences and opening sentences of paragraphs. "Crustal rocks contain an interesting historical record." |
Use to describe experimental setup and procedures. "Initially, a fractured steel specimen was plated with electroless nikel and secured in an. . . " |
| x |
When referring to another's work or figure/table. "Feldman explains. . . ." "Figure 2 illustrates. . . ." |
In formal abstracts that introduce papers. |
| x | x |
When it makes the most sense to emphasize the receiver of the action rather than the doer. "The samples should be monitored regularly and should be dried carefully once they are cooled." |
| x | x |
When emphasis or coherence demands it. "One facet of multiple phase transformation can be seen through an examination of the gas gathering process. This process was completed by . . . ." |
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