Presumably you want to use the results (statistics) of your questionnaire as data to prove or disprove some hypothesis. How you choose your sample will determi

Presumably you want to use the results (statistics) of your questionnaire as data to prove or disprove some hypothesis. How you choose your sample will determine whether your results reflect the actual population. You should consult a good statistics text to learn about selecting your sample. Self-selection is generally not a good strategy. How you frame questions in your questionnaire will also have a significant impact on the answers you receive. If you expect to rely on the answers, you need to study and characterize the questions. Wording and grammar and question redundancy are important. Questionnaires need to be validated experimentally. There is, of course, a substantial literature on questionnaire formulation. One more thing, p-value tests of significance, once the gold standard, are now controversial (at best) and discredited (in some circles). https://en.wikipedia.org/wiki/P-value https://en.wikipedia.org/wiki/P-value