When explaining an experiment from a paper which one of the following seems more suitable and natural.

In this paper they study the genetic structure of human body. They have examined over 100 patients...

Or should it be simple past:

In this paper they study the genetic structure of human body. They examined over 100 patients...


3 Answers 3


In this particular context I think neither form is really correct. The preceding sentence uses present tense "they study", so for consistency it should be...

They examine over 100 patients...

  • 1
    Good point, except wouldn't it be better all around to say '...they studied..'?
    – Mitch
    Apr 4, 2012 at 17:36
  • @Mitch: Per my comment to John's answer, I personally have misgivings about the word study itself here. But so far as tense is concerned, the present actually seems to be the most common option if you scan some written instances of "in this paper we" Apr 4, 2012 at 17:43
  • @FumbleFingers- Thanks. I have another related question for an activity happened in the past, while explaining the whole story in present: In this paper they examine the structure of the human body. Aside from current research, they also examine research papers that are published in 1997. Can this part be in simple present or should it go to simple past(were published)? Is it well written? What is the tense if we remove 'are' from 'are published'?
    – Noah
    Apr 5, 2012 at 6:16
  • 1
    @Noah, I think I would phrase it: In addition to current research, they also examine several research papers published in 1997." It could also be phrased, "... that were published in 1997" or you could drop the papers part altogether and say, "In addition to current research, this paper also examines research published in 1997."
    – Jim
    Apr 5, 2012 at 7:39
  • 1
    @Noah, simple past. The full expansion would be: "this paper also examines research [that was] published in 1997."
    – Jim
    Apr 6, 2012 at 6:38

Neither. All four sentences have article mistakes. They should be

  • In this paper they study the genetic structure of the human body. (the required here)
  • They (have) examined over 100 patients...

As for the perfect construction with have, probably that's not necessary.

Scientific reports generally use specific tenses and constructions for different parts of an experimental paper. For instance, if the experimenters built a piece of equipment that is still available, they might use a perfect construction, but, if the piece of equipment is not still available, they'd use simple past instead.

Your best course of action is therefore to use whatever tenses and constructions the paper uses in your own report. If they wrote "We examined", you write "They examined"; if they wrote "We have examined", you write "They have examined".

Don't try to second-guess the author, or the author's grammar, unless you're the editor of the journal it's being published in.

  • Thanks. What if it's a survey that they have taken?
    – Noah
    Apr 4, 2012 at 17:14
  • I don't think you can put a survey into a "taken" state, so *I will have the survey taken by next week sounds very bad to me. I will have the exam taken by next week, on the other hand, sounds fine. It's a metaphor of checking things off on a list. Apr 4, 2012 at 17:17
  • Personally I think scientific papers don't usually study things - they tend to examine, explore, prove. Or maybe undertake a study, implying that the paper will report/analyse the results of the study. Apr 4, 2012 at 17:24
  • Sure. Lots of choices to go around, and lots of different styles for different sciences. Apr 4, 2012 at 17:34
  • @JohnLawler- No, I mean writing a review for an already completed survey paper.
    – Noah
    Apr 5, 2012 at 3:39

They are both correct.

The use of the Present Perfect form denotes that the action happened in the past but the results of the action are still important in the present. The exact time of the event isn't stated because it isn't important.

The Simple Past form shows that the action happened in the past without any repercussions for the present.

I believe that the choice of the form given to the verb depends on the meaning the speaker or the writer wants to convey.

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