State the single overall aim clearly. It is often useful to express this as a question:

  • How many …?
  • Is there a relationship between ...?
  • What are …?
  • How much …?
  • Why do …?

or you may use phrases such as:

  • Patterns of …
  • An evaluation of ...
  • A literature review of
  • Secondary analysis of ...
  • An assessment of ...

Do not include methods: your aim is not, for example, "to carry out a survey" but to summarise the overall purpose of doing so.