Introduction

This article will help you understand and use Optional Questions in your Questionnaire.

Optional Questions

Optional questions are a set of questions that are displayed to the user on random, based on a probability value.

You can add one or more optional questions in each group and let the group decide which ones to display.

Group Maximum Number of Questions

As we mentioned in a previous article, each group has a field called "maximum number of questions". This field determines how many questions of the group will be displayed to the end-user, in display order as they appear in the questionnaire design section.

Non-Optional Questions

Starting with the non-optional questions, group will include all the non-optional questions until it reaches the max or until they run out and then start selecting from the optional questions based on their probability. A group may select 0 or more optional questions until it reaches the max value.

Question Probability

You can mark a question as optional by setting Optional Switch to "on" and setting a probability, as it appears on the following screenshot:

You can either select one of the preset values:

or select Custom and fill in the probability of the question.

How Probability Works

You can work with question probability in various ways:

• Set a fixed probability for more than one questions and select a set of them.
• Set auto probability for some or all of the questions

Fixed Probability

You can set your question a fixed probability based on the given preset values or a custom value.

NOTE: If the number of optional questions is less than the number of questions needed to fill the group, all questions will be selected. Only questions with 0 probability will be skipped.

Normally, the probability values should sum up to 100%, but you can sum up to less than that to leave room for not selecting a question.

Example:

From the above example, there is a 5% probability of not selecting any question.

With 2 questions left for the group, we could have the following steps:

1. There is 95% probability of selecting the first question
2. Select "Question 2"
3. There is 65% (95% - 30%) probability of selecting the second question
4. Select No Question

Or the following:

1. There is 95% probability of selecting the first question
2. Select No Question
3. There is 95% probability of selecting the second question
4. Select "Question 4"

With 1 question left for the group, if the sum of probabilities do not sum up to 100%, there is change that no question is selected.

Auto Probability

You can set auto-probability to questions that you do not wish to have a specific probability but share the remaining probability equally. This allows you to:

• Have as many questions as you like, with equal probability without editing the values
• Have questions with auto probability and questions with fixed, to provide more weight

Example:

In the above example, "Question 3" and "Question 4" will share the remaining 20% over their count (20/2 = 10% each).

Examples

Assume we have a group with 5 maximum number of questions:

Example 1:

Example 2:

Example 3:

In the above example we can see that there is no question selected for no5. This is a probability that might happen if questions' probability do not sum up to 100%.

Example 4:

In the above example we can see that regardless of the display order, the non-optional questions will be selected first and then the optional questions.