Is this also possible when I need to calculate an error percentage across all items (but only those in the questions answered)?

Question

There are 10 multiple choice questions with 9 items each, but for some of the items within each question it is correct to click/select them, for others to not click them.
So this needs to be defined before calculating the score.
Then, the error percentage should be calculated by dividing the sum of the wrong choices on all items by the sum of the items in the questions that were answered. Some of the questions are on pages that will not be displayed if participants are too slow (there is a time limit across all 10 questions), so these are the not answered questions.

The code so far is:

if (value('D208_03') == 1) {     
$ergebnisD2Z1B1 = 0;     
} elseif (value('D208_03') == 2) {  
$ergebnisD2Z1B1 = 1;

This is repeated for each item in each question, then summed up and divided by the total number of items.

But how do I do this when some of the questions might not be answered?

Answer 1

So this needs to be defined before calculating the score.

I recommend using an array for such an application:
Score Responses

Some of the questions are on pages that will not be displayed if participants are too slow

So, you will have to find out which items hav been displayed - that may be the most ambitious part, and if you're using JavaScript, I recommend that you store the number of items into an internal variable, so you can be sure. If you're using an array for counting the points, then it's easy to only add those items that have actually been shown.

The point is that you cannot not answer a multiple choice item. Therefore, the question is about whether it was visible or not. As displaying an item is done by JavaScript on the browser-side, SoSci Survey won't know unless you store that information.