1. Closed: respondents must choose their answer from a limited range of possible answers that the researcher has decided upon in advance. Open: respondents are free to give whatever answer they wish.
  2. It gives direction to the research and a focus to the question asked
  3. An aim is a statement of what the researcher intends to investigate or find out; a hypothesis is a statement of an explanation that is to be tested against evidence.
  4. A trial run carried out on a small sample before the actual survey to iron out problems, clarify questions, give interviewers practice etc.
  5. The process of defining a concept in such a way that it can be measured.
  6. By dividing the population to be studied into known groups before sampling (such as age or gender), so that a sample is made more representative.