Display Logic using "Not Equal" uses inverted conditionals | XM Community
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Hello,

Today, I want to share a case that happened to me while using display logic, and from what I've researched, it's still not documented in the Qualtrics community or support.

I would also like to know if my perception is wrong, or if Qualtrics has a specific way of handling these cases.

I had to use display logic for 3 questions in such a way that everyone could see these questions EXCEPT those who belonged to 2 specific combinations of Country AND Company.
 

As an example, the logic initially configured was as follows:
 



I realized that the display logic was not working correctly, and after several tests and iterations, I concluded that when using the "Is not" or "Is not equal" operator, the "And" and "Or" conditionals are inverted, making each one behave oppositely. So, if you configure an "And", Qualtrics will interpret it as an "Or", and the same happens with the opposite case.

Therefore, the correct logic configuration would be as follows:

 

In my opinion, this goes against the usual logic for configuring conditionals, but in the case of using "Is not", it is an important consideration.

If anyone else has worked with this element or knows if this topic is specified in the support documentation, I would appreciate it if you could let me know.

Thank you very much to everyone who took the time to read the post.

Logic with negations of conjunctions and disjunctions can be tricky.

You want to exclude when ((A=w and B=x) or (A=y and B=z)).

To invert this condition, you can apply the negation directly: not ((A=w and B=x) or (A=y and B=z)).

Using De Morgan's Laws, this can be transformed to: not (A=w and B=x) and not (A=y and B=z).

De Morgan’s transformation of this expression would be: (not (A=w) or not (B=x)) and (not (A=y) or not (B=z))"

This final expression (not (A=w) or not (B=x)) and (not (A=y) or not (B=z)) represents the condition under which "P" should be displayed — essentially, whenever it is not true that A is w and B is x, or A is y and B is z.

​@Juan Zapata : Yes, this process involves applying mathematical logic before implementing display logic directly to the relevant question.

If you wish to exclude responses based on a complex condition, it is essential to approach it mathematically. This means you should invert your logical operators: where you have an AND condition, consider using OR, and vice versa.

For instance, if you want to exclude participants who meet both conditions A and B, you can express this mathematically as follows: Exclude (A AND 😎 is equivalent to (NOT A) OR (NOT 😎. This transformation allows you to effectively manage the display logic in Qualtrics.

I hope this explanation clarifies the concept and assists you in setting up your display logic effectively.

Hi

Thank you to everyone for your responses.

I hadn't thought about the complete negation of the entire logical formula, this helps me approach these problems with a broader perspective next time.

Thank you so much!

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