The way in which QlikView's associative engine works means Nulls don't really exist in the data it holds, a Null is simply an absence of a data item.For example if a field value is missing we can’t make selection on empty list box. We can replace these null values with our required values(NA,0, etc) .
The link to the document by Henric Cronström is extremely useful. I have also been working handling NULLs in a data model recently and have written the attached. I hope this helps!
