Use of passive voice

By Lu Chen

April 4, 2017

When you write what you did in your research, the choice of voice depends on the specific requirement of your target journal or conference. So check with the Guide for Authors in the beginning. If it is your master or PhD thesis that you are writing, you had better check with your university or supervisor. No matter which voice you use, please bear in mind that the voice should be kept consistent throughout the paper.

 The passive voice is commonly used to describe what you did, but there are also some journals suggesting that authors use the active voice instead of the passive voice. For one thing, sentences in the active voice are usually more succinct than that in the passive voice. For example, “…waste gas was purified by the scrubber…” can be shortened into “…the scrubber purified waste gas”, which saves space and time. For another, the active voice is more concise. In sentences using the passive voice in academic writing, the agent (the person who does an action) is often left out. In other words, we say that something was done but we don’t say by whom. So readers may get confused about the person who did the action. Is the agent the author? Or other researchers? While in the sentence using the active voice, the agent is mentioned clearly. For example, “In the first step, a case study to clarify the present situation was conducted.” vs. “In the first step, we conducted a case study to clarify the present situation.” However, despite of these advantages of the active voice, it is still more conventional to use the passive voice, especially for master or PhD theses. For journal or conference papers, sometimes you can use the active voice (we did) if you are a member of the research team, while for master or PhD theses, you worked alone and it is inappropriate to use the first person singular (I did).

 One problem arises when you write with the passive voice. As mentioned above, the agent is often left out in the passive voice, which makes it difficult for readers to separate your work from other researchers’ work. On the one hand, one way to make your contribution easy to identify is to add phrases such as “in this study” and “in our experiment/simulation”. For example, “In our experiment, the following two approaches were adopted to achieve this purpose.”. Besides, in the section of Introduction, you can also use a dummy subject, such as “this article” and “the present paper”, to take the place of the agentless passive voice. For example, “This article proposes a method for finding the relationship between patent documents and classifying them…”. On the other hand, when you mention other researchers’ work, mark the references clearly. For example, “In Dirichlet Mixtures (DM) (Yamamoto et al., 2005), the multinomial distributions can be estimated by Collapsed Gibbs Sampler (CGS) (Liu, 1994) or Collapsed Variational Bayesian (CVB) inference (Teh et al., 2006).”.

 Another issue is on the choice of tense when describing your research procedure with the passive voice. You need to distinguish what you did from standard steps, i.e. what is normally done or how a piece of equipment is normally constructed. You still need to check with the Guide for Authors, but wherever possible it is much clearer to use the present simple passive for standard steps and the past simple passive for what you did. Because the agentless passive voice is normally used in academic writing, the only way to help readers identify is the correct use of tense. Take the following paragraph as an example.

“Our experimental procedure is as follows. First, seawater is preheated to its bubbling point. Next, the preheated seawater enters the distillation column and evaporation takes place. Then, steam from the evaporated seawater in the distillation column entered a compressor outside the distillation column and was compressed into superheated steam. The superheated steam was introduced back into the distillation column with a hollow immersion tube heater and in turn provided latent heat for seawater evaporation. Finally, the condensed superheated steam coming out of the distillation column provided sensible heat for the seawater preheating.”

In this example, the first two steps are written in the present simple passive/active, while the last two steps the past simple passive/active. It is because of the change of tense that readers can understand that the last two steps are the authors’ original and innovative work.

References

Glasman-Deal, Hilary. (2010). Science research writing for non-native speakers of English. London: Imperial College Press.