The active voice promotes simple, straightforward writing. As such, most scientific journals encourage the use of the active voice over the passive voice [1].
Active voice – the subject acts.
Passive voice – the subject is acted upon.
You will use a variety of tenses when writing a scientific paper. Please see our “Verb tenses in a scientific manuscript” post. Here are some examples of the active/passive voice used in different tenses.
Present tense – tense often used in the Introduction/Discussion/Conclusion
Example 1:
Active: Vitamin A increases the risk of hair loss.
Passive: The risk of hair loss is increased by vitamin A.
Example 2:
Active: Volatile organic compounds (VOCs) emitted from industries and vehicle exhausts can induce a series of environmental problems, including photochemical smog, broken ozonosphere, and environmental pollution.
Passive: A series of environmental problems, including photochemical smog, broken ozonosphere, and environmental pollution, can be induced by volatile organic compounds (VOCs) emitted from industries and vehicle exhausts.
Present tense – tense often used for Aims
Example 1:
Active: In this study, we present our design of an electric hot water tank.
Passive: In this study, a design of an electric hot water tank is presented.
Example 2:
Active: This study develops an efficient methodology to examine a space–time continuous dataset for urban irrigation water use.
Passive: An efficient methodology to examine a space–time continuous dataset for urban irrigation water use is developed in this study.
Present perfect – tense often used in the Introduction/Discussion/Conclusion
Example 1:
Active: Previous studies have used comparative analysis of ORF2 sequences to elucidate phylogenetic relationships among different FCV isolates.
Passive: Comparative analysis of ORF2 sequences has been used in previous studies to elucidate phylogenetic relationships among different FCV isolates.
Example 2:
Active: Only a small number of empirical studies have focused on the patterns and mechanisms behind disease clusters at small spatial scales, especially in wild host–pathogen systems [2].
Passive: The patterns and mechanisms behind disease clusters at small spatial scales, especially in wild host–pathogen systems, have been focused on by only a small number of empirical studies [2].
Past tense – tense often used in the Materials and Methods/Results
Example 1:
Active: We determined the presence of larvae by dip netting.
Passive: The presence of larvae was determined by dip netting.
Example 2:
Active: We evaluated the number of haplotypes (h), haplotypes (Hd), and nucleotides (π) using the DnaSP 5.10 program [2].
Passive: The number of haplotypes (h), haplotypes (Hd), and nucleotides (π) was evaluated using the DnaSP 5.10 program [2].
Example 4:
Active: We found a strong correlation between above-ground and below-ground biomass accumulation in Platanus occidentalis.
Passive: A strong correlation was found between above-ground and below-ground biomass accumulation in Platanus occidentalis.
However, you should aim to make the language of your article as reader-friendly as possible. Therefore, it is acceptable to use the passive voice when it is required.
When to use the passive voice [3]:
- To emphasize the product (receiver) rather than the agent (performer)
The risk of hair loss [product] is increased by vitamin A [agent].
- To keep the subject and focus consistent throughout a passage
Female pattern hair loss is common but estimates of its prevalence have varied widely. The risk of female pattern hair loss is increased by vitamin A.
- If you do not wish to name the subject
The procedures were somehow misinterpreted.
- To describe a condition in which the actor is unknown or unimportant
Every year, thousands of people are diagnosed with cancer.
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References
1. Sainani K, Elliott C, Harwell D. Active vs. passive voice in scientific writing. [Webinar]. American Chemical Society. 2015 Apr 8. Available from: https://www.acs.org/content/dam/acsorg/events/professional-development/Slides/2015-04-09-active-passive.pdf [Accessed 20th June 2016].
2. Plotnick J. How to use active voice in the sciences. University College Writing Centre, University of Toronto, Canada. Available from: http://www.writing.utoronto.ca/advice/specific-types-of-writing/active-voice-in-science [Accessed 20th June 2016].
3. The Writer’s Handbook. Use the active voice. The Writing Centre, University of Wisconsin, USA. Available from: http://writing.wisc.edu/Handbook/CCS_activevoice.html [Accessed 20th June 2016].