Hi there,
I am sorry to have to ask such a simple question but am a bit confused about between subjects assignment to groups. In a recent experiment I set two groups of participants to receive two different versions of the task. I set group assignment to be 'random' hoping that equal numbers of subjects would be assigned to group 1 or 2 (I got this from the documentation:
https://www.millisecond.com/support/docs/current/html/viewer.htm#https://www.millisecond.com/support/docs/current/html/language/attributes/groupassignment.htm)<expt>
/blocks = [1=informedConsentBlock;2 = initialInstructions; 3 = survey.initialInstructionsSurvey; 4 =practice; 5 = faceExptInstructionsReward;
6 = experimentWarning; 7-10 = faceBlocksReward; 11=DASS; 12 = summary; 13=recordEmail]
/ subjects = (1 of 2)
/ groupassignment = random
/ postinstructions = (page.thankYouScreen)
</expt>
<expt>
/blocks = [1=informedConsentBlock;2 = initialInstructions; 3 = survey.initialInstructionsSurvey; 4 =practice; 5 = faceExptInstructionsNoReward;
6 = experimentWarning; 7-10 = faceBlocksNoReward; 11=DASS; 12 = summary; 13=debriefblock]
/ subjects = (2 of 2)
/ groupassignment = random
/ postinstructions = (page.thankYouScreen)
</expt>
Although participants were assigned by Inquisit to group 1 or group 2, this variable seems to be totally meaningless and does not correspond to the version of the experiment that they did! Luckily I have been able to work out what version they actually did from the block code but I am intrigued as to what exactly went wrong. Millisecond received subject IDs from SONA but it does not seem as if the odd numbers did v1 and the even numbers did v2. Instead it seems totally random as to which version of the task they did (and there are 2/3 of people assigned to the v1). Could you please advise on how should I have randomly assigned pp to the two versions of the task (without relying on ID number?).
Much appreciated