I am trying to figure out how to do this.

On page 1 of my survey, I asked the participant age (code:age)
On page 2, I asked at what age was the participant was diagnosed with a disasse (code:agedx).

So I want to prevent an answer where the agedx is greater than age. I started off by creating a flag (equation variable) where I set it as if(age1 < AgedxkN, 2, 1). And I created a text display code where if flag==2 then display the text (A warning saying "your age dx is greater than your age"). BUT the participant can still hit next and continue on to the survey.

So basically, if the subject is 29 year old... his diagnosed age should be less than or equal to 29. So if the subject answered 32 for example, I want to alert the subject and would not allow him to continue onto the survey until that answer is fixed.

I want the participant to be able to submit a valid answer (so flag==1), before being able to continue. How can I do this?

I am unsure if it matters, but age (both questions) are being recorded using a drop down box.

pennywaltz wrote: I am unsure if it matters, but age (both questions) are being recorded using a drop down box.

We don't have validation for drop down.

Better to use "numeric" question type or short text : www.limesurvey.org/manual/Question_type_...8em_validation_sq.29

just to understand the example you linked to me:

(this / 3) == floor(this/3)

This is basically the code right? and this goes into the validation box?

so would I type in agedx<=age in the validation box, so where the agedx must be less than or equal to age

No,

Not in validatio box , in advanced settings part.

But with numerci question type : www.limesurvey.org/manual/Question_type_...28max_num_value_n.29 use directmly max value.

Denis