A survey is used to get people’s opinions about something. A survey consists of participants (a sample of or the full population), a method of data collection (usually a questionnaire either handed out or accessed online), and methods to analyze the data. In a survey it is important that the population sample is representative of the population as a whole, otherwise general conclusions can not be drawn.
A questionnaire consists of a number of individual questions that can have qualitative or quantitative answers. It is best used when you want to include many participants, and the answers do not have to be very detailed or informative. A questionnaire can consist of only qualitative questions, only quantitative questions or a mix of both.
For qualitative questions, the answers consist of free text or multiple-choice, for example asking participants what features they liked the most in a piece of software.
For quantitative questions, it is common to use a Likert scale where participants rate their level of agreement on a statement. An example of a five-level Likert scale is:
- Strongly disagree
- Neither agree nor disagree
- Strongly agree
Likert scales can be of any level, but five and seven are very common. It is also possible, although not very common, to use an even number of levels (for example four or six). In this case, there is no neutral answer (neither agree nor disagree).
Another scale that can be used in quantitative questionnaires is the rating scale. Rating scales have an interval (1-5 or 1-10 is common) or a ratio level (twice is much, three times as much, etc.). Rating scales are for example used when asking participants how useful they think a piece of software is, or how much they value a feature in the software.
There have been lots of research on how to plan, design and conduct a questionnaire study, and it is important that you read up on this research before you plan your own study. Two good reports are Guidelines for conducting and reporting case study research in software engineering and Qualitative Interview Design: A Practical Guide for Novice Investigators.