Data can come in two forms:

  • Qualitative (words)
  • Quantitative (numbers)

Quantitative data can be:

  • Discrete i.e. can only take certain values  – e.g. the number of children in a class
  • Continuous i.e. can take any value in a range – e.g. weight


To collect quantitative data you need to group it into classes. Discrete data has “gaps” between classes (e.g. 1-2 children, 3-4 children etc). Continuous data does not..and as such is often written as inequalities (e.g. 30lbs < weight ≤ 50lbs, 50lbs < weight ≤ 70lbs etc).

Questionnaire Answers

You might be asked whether a questionnaire is good or bad. For a questionnaire to be a good one the questions must be:

  • Clear and easy to understand
  • Easy to answer
  • Not misleading or biased
  • Easy to analyse

So avoid open ended questions, questions with possible answers like “a little bit” which are open to interpretation, and questions that suggest an answer.