Active versus passive voice in scientific writing

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 versus passive voice

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]:

  1. To emphasize the product (receiver) rather than the agent (performer)

The risk of hair loss [product] is increased by vitamin A [agent].

  1. 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.

  1. If you do not wish to name the subject

The procedures were somehow misinterpreted.

  1. To describe a condition in which the actor is unknown or unimportant

Every year, thousands of people are diagnosed with cancer.

[1] Sainani, K., Elliott, C. & Harwell, D. (2015) Active vs. passive voice in scientific writing. American Chemical Society. Webinar. Available at: https://www.acs.org/content/dam/acsorg/events/professional-development/Slides/2015-04-09-active-passive.pdf [Accessed 20 June 2016].

[2] Plotnick, J. (2016) How to use active voice in the sciences. University College Writing Centre, University of Toronto, Canada. Weblog. Available at: http://www.writing.utoronto.ca/advice/specific-types-of-writing/active-voice-in-science [Accessed 20 June 2016].

[3] The Writer’s Handbook. (2014) Use the active voice. The Writing Centre, University of Wisconsin, USA. Weblog. Available at: http://writing.wisc.edu/Handbook/CCS_activevoice.html [Accessed 20 June 2016].