====== Multiple Choice ======

With a multiple choice you can select none, one or more answers. By default, browsers display the input fields differently (square under Windows) than with simple selection questions (round under Windows).

The data structure (variables) looks significantly different with a multiple selection than with a normal selection question. While a normal selection question has only a single variable, the multiple choice question has one variable per selection option. Because each selection option can be selected (code 2) or not selected (code 1).

===== Missing Answers =====

In a multiple choice question the participant can __not__ give no answer. If you set a checkmark, this means "yes", if you do not set a checkmark, this means "no". Because of this there is no logical difference, if an answer was given or if the item was skipped.

However, each multiple selection has an additional variable that specifies the number of selected options (positive code or 0) or the code of the alternative response (negative code).

===== Exclusive options =====

A multiple selection allows different types of exclusive options, i.e. options that cannot be selected together with other options. For example this could be "none of the above".

  * Enter an option in the question under //alternative options//. This option is then separated from the other options at the end and also highlighted visually.
  *Enter a regular option, then select the option in the question catalogue on the left __or__ click on the detailed view next to the option ({{:button.edit3.png?nolink|Symbol: Bearbeiten}}). Tick there the //exclusive option//.
  * Use the JavaScript code ([[:en:create:javascript]]) below so that two options cannot be selected at the same time. Please note that this variant of the restriction is only cosmetic, it is only monitored when JavaScript is activated.

<code javascript>   
<script>
function CheckboxExclusive(optionA, optionB) {
    var oa = document.getElementById(optionA);
    var ob = document.getElementById(optionB);
    
    oa.addEventListener("click", function() {
        if (oa.checked) {
            ob.checked = false;
        }
    });
    ob.addEventListener("click", function() {
        if (ob.checked) {
            oa.checked = false;
        }
    });
}

// For each line, enter the identifiers of the options,
// that should not be selected at the same time.
// Add further lines if necessary.
new CheckboxExclusive("AF04_01", "AF04_02");
new CheckboxExclusive("AF04_03", "AF04_04");
</script>
</code>