Home Questions Randomize blocks

Randomize blocks

andpru asked 8 years ago
Is there and easy way to randomize blocks?    This is, say I have  Block 1 = [1 2] Block 2 = [1 3] Block 3 = [1 4]   Is there are way that the blocks will be executed in a random order with each loading? I thought this used to exist at some point, the term superblock comes to mind ...   ap.  
2 Answers
Duncan McLean Staff answered 8 years ago
Hi Andrew, The "super block" idea has been on our feature list for a long time but it has not been implemented, so at the moment there is no way to do exactly what you are asking for. There are two main work-arounds I can think of:
  1. Design each trial to contain 2 trials internally. This option obviously falls apart pretty quickly if you need to have more than 2 trials in a block.
  2. Have multiple protocols with the blocks in different order and select a random protocol to run for a subject
Certainly neither of these are perfect. How much do you need this feature? We'd love feedback about this so we can prioritize features for upcoming releases. All the best, Duncan
apruszynski replied 8 years ago

Yes, I have implemented both those workarounds and they work fine. Just thought I remembered the superblock idea being already in a previous version. But I guess that’s faulty memory. I am not desperate for this feature.

Duncan McLean Staff answered 4 years ago
NOTE: The answer to this question seems to have been lost when we moved the website. As of Dexterit-E 3.8 this is possible with a bit of extra copy and paste. As of Dexterit-E 3.8 it is possible to use brackets around items in a block list. The bracketing conveys the meaning of grouping TP's together. Section 6.11 of the Dexterit-E 3.8 User Guide has detailed examples. The short answer for you is to set up a single block as: ([1, 2], [1,3], [1,4]) The numbers in [ ] will always be held together as a group and run in the exact order given. The surrounding ( ) that means that the order of the blocks inside will be randomized. Duncan