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Not sure if this will be of use to anyone as it is the first time I have been asked to do this. Basically the researcher wanted a way to display 4 statements in a random order, showing 2 at a time and then the statement that is selected is moved to the next question to be paired with one of the remaining statements, this is then repeated with the final statement.

After looking through previous replies from here I have put together this short survey that carries out this exercise. It is a little bit lengthy (I am sure it can be streamlined) but for now it does what we want.

 
 

Unsure i understand it (and i don't look at the survey)

But maybe it can be interesting to have it here : www.limesurvey.org/manual/ExpressionScript_examples/en ?

Hi,
I remember that I did something like this some/many years ago.

Is it true that this only works in "question by question"?

I have a different approach.
I use a hidden multiple question (HM) which is used as array filter for the single questions.
After each comparison this hidden question is reset by an equation.

There are only six options to select 2 out of 4 statements
12, 13, 14, 23, 24, 34 (order doesn't matter as we display randomly)
And because the remaing two statements are randomly displayed there are 12 options in total.
1234, 1243, 1324, 1342, 1423, 1432, 2314, 2341, 2413, 2431. 3412, 3421

Now we create a random number (eqRand) (1-12) to select one order in an equation (eqPool)
{if(eqRand==1,'1234', if(eqRand==2,'1243', if(eqRand=,'1324', if(eqRand==4,'1342', if(eqRand==5,'1423', if(eqRand==6,'1432', if(eqRand==7,'2314', if(eqRand==8,'2341', if(eqRand==9,'2413', if(eqRand==10,'2431', if(eqRand==11,'3412','3421')))))))))))}

The hidden multiple question is set by this equation
{HM_1=if(strpos(join('#',substr(eqPool,0,2)),"1")>0,"Y","")}
{HM_2=if(strpos(join('#',substr(eqPool,0,2)),"2")>0,"Y","")}
{HM_3=if(strpos(join('#',substr(eqPool,0,2)),"3")>0,"Y","")}
{HM_4=if(strpos(join('#',substr(eqPool,0,2)),"4")>0,"Y","")}

The leading "#" to avoid an index of "0" in "strpos"

Q1 now a list(radio) with array filter "HM"

After this qestion HM is reset with this equation
{HM_1=if((substr(eqPool,2,1)=="1") or (Q1==1),"Y","")}
{HM_2=if((substr(eqPool,2,1)=="2") or (Q1==2),"Y","")}
{HM_3=if((substr(eqPool,2,1)=="3") or (Q1=),"Y","")}
{HM_4=if((substr(eqPool,2,1)=="4") or (Q1==4),"Y","")}

Meaning: If the statement appears on the third place of the string OR if it was selected in Q1, set it.

And the same procedure after this second question
{HM_1=if((substr(eqPool,3,1)=="1") or (Q2==1),"Y","")}
{HM_2=if((substr(eqPool,3,1)=="2") or (Q2==2),"Y","")}
{HM_3=if((substr(eqPool,3,1)=="3") or (Q2=),"Y","")}
{HM_4=if((substr(eqPool,3,1)=="4") or (Q2==4),"Y","")}

Set the statement at the fourth place and the answer of Q2

Here two examples (for information I show the selected order.
 



And it is rather short
 
 
Just another idea.

Joffm