Tutorial: RBG (14/21)

Location

…\DirectRT\samples\3 ordering trials\rbg.csv

Description

The following text is taken from the interactive tutorial located in the help folder after installation.  You may prefer to print these pages rather than having them on-screen during the tutorial.

A second basic method of randomization, RBG, stands for Randomization Between Groups. As with RWG, every trial that is assigned the same RBG value belongs to the same RBG group. The difference is that instead of randomizing the trials within the group, all the items are treated as a set to stay together. DirectRT will then randomize the order in which the different RBG groups is presented.

Open the input file and take a look at the RBG values. Notice that there are three RBG groups (1, 2 and 3). Run the session and notice what happens to the ordering of the trials. You'll notice that the order of the trials within each group doesn't change-just the ordering of the groups themselves. Also notice that any trials with an RBG value of 0 never moves. DirectRT knows not to include any trial with a value of 0.

Important: In order for trials to share the same RBG value, they all need to be together in one continuous set.