You can see the questionnaire as it will be shown to respondents and enter test answers without influencing your survey results.
Testing the questionnaire is important to:
Click on "View and test the questionnaire".
Near the top of the questionnaire editor, there is a link "View and test the questionnaire". Click to open a new window that shows the questionnaire as it will be shown to your respondents.
At the top, there is a brief explanation of the "test mode", written in blue. When this message is shown, any answers you enter are automatically deleted after about 15 minutes. This means: you can enter as many test answers as you like, without having to fear that they will interfere with your real survey results. However, please keep in mind that they will disappear automatically after a while, which can be surprising if you return to the testing window after leaving it alone for more than 15 minutes. Also, as long as the testing answers are still in the database (during the first 15 minutes after you entered them), they will appear in reports and on the real-time results page.