Translation:What is the purpose of the research?
I disagree, an aim is more of a 'goal' or an 'objective'. A purpose might be subtly different. An example: The purpose of the investigation is to bring a murderer to justice. Therefore the aim is to match the correct DNA found at the crime scene. This really is a very, very subtle difference though so I can see how you could argue it.
Whoever programmed this should accept the following translations as well:
"What is the research's purpose?";
"What is the investigation's purpose?" and
"What is the purpose of the investigation?"
They're all obviously correct. Instead, I was penalized for using (1) and (2), which makes me feel dead certain that they would have taken a point off if I used (3).
From Word Reference: investigación nf (indagación, pesquisa) investigation n (commission) inquiry, enquiry n (UK) inquiry n investigación nf (estudio) (medical) study n (general) research n Clearly, the term "investigation" should be accepted, as well as the shorter genitive forms.