randomly assigning each participant to one of four conditions?


randomly assigning each participant to one of four conditions?

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 Hi Dave,

I have two questions that I need your help.

My experiment has 4 conditions and I want to randomly assign one condition to each participant (so each participant should only complete one of the four conditions).

Right now my script looks like this:

*******************************************************************************************************************
*******************************************************************************************************************
EXPERIMENT
*******************************************************************************************************************
*******************************************************************************************************************

<expt conditionCOG9>
/subjects = (1 of 4)
/groupassignment = random
/ blocks = [
1 = cogcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog9;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>

<expt conditionCOG2>
/subjects = (2 of 4)
/groupassignment = random
/ blocks = [
1 = cogcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog2;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>

<expt conditionsup9>
/subjects = (3 of 4)
/groupassignment = random
/ blocks = [
1 = supcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog9;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>

<expt conditionsup2>
/subjects = (4 of 4)
/groupassignment = random
/ blocks = [
1 = supcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog2;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>


*******************************************************************************************************************
End of File
*******************************************************************************************************************



And my current setting for Subject IDs is “User entered” and I will be asking for an email address.

My questions are:

1. does my script look like it is doing what I want to achieve? (randomly assigning each participant to one of four conditions)

2. do I have to change the current setting for subjects IDs for my study to run smoothly? (e.g., change it to “Random selection without replacement” and enter 4 for the section where it asks for “enter the total number of groups.” like the picture I am inserting here

As always, thank you for your help!! 



Dave
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Group: Administrators
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hongseonkim@mail.adelphi.edu - Sunday, March 31, 2019
 Hi Dave,

I have two questions that I need your help.

My experiment has 4 conditions and I want to randomly assign one condition to each participant (so each participant should only complete one of the four conditions).

Right now my script looks like this:

*******************************************************************************************************************
*******************************************************************************************************************
EXPERIMENT
*******************************************************************************************************************
*******************************************************************************************************************

<expt conditionCOG9>
/subjects = (1 of 4)
/groupassignment = random
/ blocks = [
1 = cogcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog9;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>

<expt conditionCOG2>
/subjects = (2 of 4)
/groupassignment = random
/ blocks = [
1 = cogcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog2;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>

<expt conditionsup9>
/subjects = (3 of 4)
/groupassignment = random
/ blocks = [
1 = supcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog9;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>

<expt conditionsup2>
/subjects = (4 of 4)
/groupassignment = random
/ blocks = [
1 = supcondition;
2 = StartInfo;
3 = Practice_EmotionalStroop;
4 = EmotionalStroopcog2;
5 = panasfinal;
6 = vamsfinal;]
/ postinstructions = (end)
/onexptend = [
values.completed = 1;
]
</expt>


*******************************************************************************************************************
End of File
*******************************************************************************************************************



And my current setting for Subject IDs is “User entered” and I will be asking for an email address.

My questions are:

1. does my script look like it is doing what I want to achieve? (randomly assigning each participant to one of four conditions)

2. do I have to change the current setting for subjects IDs for my study to run smoothly? (e.g., change it to “Random selection without replacement” and enter 4 for the section where it asks for “enter the total number of groups.” like the picture I am inserting here

As always, thank you for your help!! 



> 1. does my script look like it is doing what I want to achieve? (randomly assigning each participant to one of four conditions)

It will assign conditions randomly per /groupassignment = random, and it will accept non-numerical, subject-entered subject IDs (such as an email address.) However, when setting /groupassignment = random, the condition assignment bears no mathematical relationship to either the group or subject ID. What you'll usually want to do on the web instead is specify the number of groups and select random group number generation in the web experiment's settings as you already have. Then, however, you'll want your <expt> elements assign conditions based on that randomly generated group number, i.e. instead of /groupassignment = random, I'd recommend you set it to /groupassignment = groupnumber. (Also see https://www.millisecond.com/forums/Topic13856.aspx )



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