A group of researchers is seeking to test whether journaling about positive experiences makes one happier. To test this, study participants are randomly assigned to one of two groups. In group 1, participants are provided with specific instructions that require journaling twice a day; specifically, about positive experiences one has had, or things that the individual is grateful for. In group 2, participants are not provided with journaling instructions, nor are they encouraged to journal. At the end of the study, participant happiness is assessed.
What type of study design has been implemented in the above example? In light of the study design being used, are there any points of caution or advice that you could provide the researchers?