When using a long form, you must use several methods to make a good user experience. For really long forms with many questions, here are several things you can try:
1. Group your questions into sections
Order your questions into manageable pieces. When you have a long form, you are likely to ask questions about many different topics. Its objective is to identify what these topics are and classify your questions into easy to understand sections.
Once you have sections, this means that you can more clearly assign where a person is in the process of completing the form. Completing sections also allows small rewards in a long and probably not fun form filling process.
2. Make the location visible
A key difference between short forms and long forms is that they require a different user experience. Short forms are completed in a couple of minutes, long forms can take hours, and people are expected to take breaks between sessions. For long forms, you must include a "you are here" feature, which keeps the person oriented and at the same time gives you the ability to estimate how much time you have left.
To make the location visible, you want to show where the person completing the form is in the process. You can use a percentage to complete the icon, page numbers, bread crumbs, loading bars, step by step, etc. There is no standard reference design for this, you will need to find a system that works with your form. In your case, I think this 2-level tree indicator is fine.
3. Set expectations before the start
To prepare the person to start the form, give as much context as possible. This will increase the completion rates for people who begin the process.
The questions that an introduction could answer are:
- Why is the person completing this form?
- How long should it take to complete the form?
- What is the schedule for the next steps?
- Do they need to prepare something in advance (for example, have a driver's license on hand or prepare documents)?
- What about the information they provide?
- Who has access to it, how will it be used, how does it meet the privacy standards?
- Does completing the form cost money?
- Don't surprise people in the end with the cost.
4. Save each question automatically
When the user fills out a long form, some problems may arise. Connection problems, session expiration, etc. Make sure that all user steps are saved and do not need to be completed again.
5. Don't ask out of focus questions
Just hide the out of focus questions surrounding the focused question for very short forms. This design is good for a simple form such as a survey but bad for long online forms with many questions.
When I complete a form like this, I can feel that my heart rate increases because I am trying to find out if I am being tricked into thinking that the form is shorter than it really is.
This style of reducing opacity for out of focus questions is not accessible. People will inevitably feel that they should read the text out of focus before it is focused. But, because the colors of the text on the screen do not meet contrast accessibility standards, readability is reduced causing any difficulty for the person trying to read the question out of focus if they can even see it in the first place.