As a simplied example of what I need to do, I ask the question:

Q1: Please indicate your age [numeric input]:
Q2: Please re-enter your age to verify [numeric input}:

I don't want the user to be able to advance to Q3 if the answer to Q1 and Q2 are different.

I see there is the question validation field -- but I gather this only allows for regular expression comparisions, but I need to just confirm that Q1 = Q2.

How can I do this?

Hi, blocka,

but I gather this only allows for regular expression comparisions

What makes you think that?
Have a look at the demo surveys about this.

Your example:
(is_empty(Q2)) OR (Q1==Q2)

Joffm

Thanks! I tried that, and I've attached my sample survey where I've been trying to do this, and it doesn't work on build 3.17.5+190604

Ah, I see, this needs to be placed under the Logic tab for the question, like this: