I need help with the following sentences,

Developed multiple models to identify dogs' behavior. Models were able to classify dogs' body positions and facial expressions.

My question is, should I use dog in singular or plural form? Because each model only able to classify one dog's behavior. But when I refer to models, can I also use dogs here since "models" is in plural form?

Maybe I should ask in this way, what are the differences between the following sentences?

  1. Developed multiple models to identify dog behavior.

  2. Developed multiple models to identify dogs' behavior.

  3. Models were able to classify dogs' body positions and facial expressions.

  4. Models were able to classify dogs' body position and facial expression.

  5. Developed multiple models to identify dogs' behavior.

  6. Developed multiple models to identify dogs' behaviors.

  • 1
    These are notes, not sentences. In context, they could make sense, but they leave out all sorts of things that sentences need. Apr 15, 2023 at 21:08
  • Can you clarify a bit more, these are notes but they don't have the same meaning, right?
    – D.dream
    Apr 15, 2023 at 22:10

1 Answer 1


If you are using multiple models, and each model describes one dog, then in total you are talking about multiple dogs, so you should use the plural, "dogs".

If there was only one model and one dog, then both should be similar.

If you had multiple models to describe one dog's behavior, then "models" should be plural and "dog" should be singular. That example sounds unlikely, but one could certainly imagine, "We created models of the Sun's behavior." Many models, but only one Sun.

Side notes: In examples 4 and 5, if you are talking about one dog, it should be "dog's", not "dogs'". In English, to make a singular possessive we usually add "'s". To make a plural that ends in "s" possessive, we just add the apostrophe.

"Behavior" is usually treated as an uncountable noun. But if you are going to use it as a plural -- which is acceptable, by the way -- its number would not necessarily match the number of dogs. One dog could have many behaviors. Or we could be discussing one behavior of many dogs. In common speech we would probably say "describe the dog's behavior" or "describe the dogs' behavior", i.e. behavior singular regardless of the number of dogs. But psychologists often refer to "behaviors", so if you're in a psychological context, maybe it should be plural in both cases.

Examples 1, 2, 5, and 6 are not complete sentences as they have no subject. Who developed these models? In some contexts incomplete sentences like this are ok where the subject is obvious. Like on a resume, we would assume the subject is "I".

  • Thanks for your answer. To be clear, let's say I have two models: one can identify whether a dog is sitting or standing in an image, and the other can identify whether the dog is barking. However, the limitation of these models is they can only detect one dog at a time, which means if there are two dogs in an image, these models would fail to work. In addition, these models don't only work for only one specific dog, but any dog. So, in this case, when I say "Developed multiple models to identify a dog's behavior", this would assume the models only work for one specific dog, isn't it?
    – D.dream
    Apr 16, 2023 at 4:03
  • @D.dream "only work for one specific dog" Not necessarily. The sentence would be potentially ambiguous. It COULD mean that the models only work for one specific dog, as in, "only works for my collie, Fido". Or it could mean that the models predict one dog's behavior at a time, but it could be any dog. I think most readers would assume the second in this particular case, because it would seem unlikely that you would do a lot of work to model the behavior of one particular dog. Except possibly as a first step to a more general model, in which case it wouldn't matter.
    – Jay
    Apr 17, 2023 at 20:49
  • That's the sort of ambiguity that we normally expect to be resolved by context.
    – Jay
    Apr 17, 2023 at 20:50

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