The difference to a single or multiple is only the Statistical Question option. All other fields have the same functionality as in a survey question, so please refer to Survey question.
A quiz can have two different types of questions: Either they have at least one correct answer (which is what you would expect from a quiz question) or you define a statistical question. A statistical question is useful when you want to evaluate the correct answers by gender, age groups etc.
A text answer in a quiz is always an answer to a statistical question.
When you provide the answers to a single or multiple choice question in a quiz, you have a checkbox in the answers that you have to check for exactly or at least one answer depending on the question type (single or multiple choice). This selection is also reflected in the answers grid.
A statistical question has no correct answer, therfore the checkbox is not available.
You may as well enter questions with a free answer text, but they are statistical questions by definition, so you cannot provide a correct answer.
Adding a question with free answer text in a quiz is the same procuder a adding it to a survey, so please refer to Survey question for further information. The Statistical Question checkbox is displayed and activated, but not enabled, so you can't change it. It has only informational character.
Updated over 2 years ago