Partially randomize blocs

Question

I want to randomize pages as follows:
a1
b1

a2
b2

I want to show them randomized
either

a1 b1 a2 b2  OR b1 a1 b2 a2

so the chance of showing a or be should be 50:50 but always question1 followed by question2  and no changing of the order within the block of pages.

Comments

what version are you using?

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I'm using version 7

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is the following ok?
b1 a1 a2 b2?

Answer 1

In version 7 and later you can use randomized blocks for this.  First create a predefined list (we'll call it BlockList) with 2 items.  Then make a constructed list where the instructions are Add(BlockList) and Randomize().

Then go into the Randomize Blocks area and you would set up the following:

Set 1
Block 1 Anchor Question 1 is a1
Block 1 Anchor Question 2 is a1

Block 2 Anchor Question 1 is b1
Block 2 Anchor Question 2 is b1


Set 2
Block 1 Anchor Question 1 is a2
Block 1 Anchor Question 2 is a2

Block 2 Anchor Question 1 is b2
Block 2 Anchor Question 2 is b2

Then you would say to use your constructed list to control the blocks.  The result is that if the constructed list comes out to be 1,2, you would see a1/b1 followed by a2/b2, and if the constructed list is 2,1 you would see b1/a1 followed by b2/a2.

Comments

cool !!

Answer 2

You can randomly generate a number between 1-2 and save it in a hidden question. You can use the function like SysRand or RandNum within the hidden question. So RandomNumber=1 is asking order 1 and RandomNumber=2 is asking order 2.

You can then set up your questions in the 2 different order sets and use RandomNumber in skips to jump the question set not relevant.

The disadvantage here is you have 4 questions (a1,b1,a2,b2) saved in 2 seperate questions each. You can combine the 2 in free format hidden questions later in your survey so you have a1tot, b1tot, a2tot, b2tot) or you can combine them in your analysis software.

This may not be the best answer but it will work.