Randomization Criteria


I have selected ‘random’ for my trials which is linked to an excel data sheet. There are two answers, A or B. Is it possible to ensure that in the randomization, there won’t be more than 3 trials in a row where A is the answer, and likewise with B?


I’m guessing you currently have two rows in your excel sheet, with details for A and B, then nReps set to the number of trials you want? You could fix the number of As and Bs by creating as many rows as you want trials in the excel sheet, just copying the A and B rows as many times as you want each answer to appear, then set nReps to 1. This way, rather than choosing either A or B randomly and repeating n times, it will make n choices from a list of A’s and B’s, allowing you to control the proportion.


Thank you so much for your reply. My excel sheet actually has a column of the stimuli and then another column saying whether it’s A or B. So I already have the amount of rows as I want trials. I need all of the stimuli for every participant and I need the order of them to be randomized differently for each participant (which I’ve done by selecting ‘random’). I just also need to ensure we won’t get three (or more) in a row that are ‘A’ or three in a row (or more) that are ‘B’.

Thank you.