Hi. I have a question about randomization. I am conducting a study where I will test the effects of a psychological intervention. The study design is as follows:

1. Collecting a base line value for all participants.
2. Assigning participants to two groups. One group gets access to the intervention directly. The other group gets only to do baseline tests and then wait for a period of time to get access to the intervention.
3. All participants take a retest.

The study design in Qualtrics is as follows:

Block 1 (Age, sex etc.).

Block 2 and 3 (Psychological self-report scales).

Block 4 (Intervention).

My question is how I best can randomize the intervention among participants (Block 4). I want the intervention to be randomly assigned to participants. And only the last block. Not all the questions. I have tried myself but I can’t seem to get it right, so my hope is that someone can help me with some tips.

Many thanks,

Niklas Lindström

Student at Kristianstad University, Sweden. Department of Psychology.