Research projects have usually been approached using either a quantitative or a qualitative approach which gives some people the idea that the approaches are mutually exclusive. However, it is possible to combine quantitative and qualitative approaches. This could be by using a qualitative study to guide the design of a subsequent quantitative study or by mixing elements of the one approach into the other.
It is more important to match the right design to the right question. Surveys (questionnaires) can often contain both quantitative and qualitative questions. The quantitative questions might take the form of yes/no, or rating scale (1 to 5), whereas the qualitative questions would present a box where people can write in their own words.