Balancing Randomization of Blocks?

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Balancing Randomization of Blocks?

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am2922	am2922 posted 5 Years Ago Topic Details Share Topic
Group: Forum Members Posts: 9, Visits: 44	Hello! I am currently running an experiment in which we are randomizing the order in which participants see different blocks. Here is the expt code that I've been using: <expt > / preinstructions = (Intro) / postinstructions = (End) / blocks = [1 = StartTone; 2 = panas_baseline; 3-4 = noreplace(human, dog) ] The randomization works great, but I've come across a problem where it seems like the human block is being shown first much more often than the dog block (human has been shown first 37 times vs. 22 times for dog first). Also, there are periods in which human is shown first 7x in a row, and then the dog block is shown first the next 3x. I'm just wondering if there is any way to balance the randomization, so that the amount of times each block is shown first is a little more even and less clustered? I appreciate any help/advice you might be able to provide with this issue!
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Dave	Dave posted 5 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 12K, Visits: 98K	+x am2922 - Thursday, January 10, 2019 Hello! I am currently running an experiment in which we are randomizing the order in which participants see different blocks. Here is the expt code that I've been using: <expt > / preinstructions = (Intro) / postinstructions = (End) / blocks = [1 = StartTone; 2 = panas_baseline; 3-4 = noreplace(human, dog) ] The randomization works great, but I've come across a problem where it seems like the human block is being shown first much more often than the dog block (human has been shown first 37 times vs. 22 times for dog first). Also, there are periods in which human is shown first 7x in a row, and then the dog block is shown first the next 3x. I'm just wondering if there is any way to balance the randomization, so that the amount of times each block is shown first is a little more even and less clustered? I appreciate any help/advice you might be able to provide with this issue! If you truly want to balance the block order, then your best bet is to treat the block order as a between subjects condition and assign half your subjects to one order, and the other half to the other order: <expt > / preinstructions = (Intro) / postinstructions = (End) / blocks = [1 = StartTone; 2 = panas_baseline; 3 = human; 4 = dog ] / subjects = (1 of 2) / groupassignment = groupnumber ... </expt> <expt > / preinstructions = (Intro) / postinstructions = (End) / blocks = [1 = StartTone; 2 = panas_baseline; 3 = dog; 4 = human ] / subjects = (2 of 2) / groupassignment = groupnumber ... </expt>
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am2922	am2922 posted 5 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 9, Visits: 44	Okay, so just to clarify, if I used this then I would control the order by either typing '1' or '2' in as the group number right before starting the inquisit task program, correct? Or does the program generate the group number and assign each participant to a group randomly? Thank you for your help!
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Dave	Dave posted 5 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 12K, Visits: 98K	+x am2922 - Thursday, January 10, 2019 Okay, so just to clarify, if I used this then I would control the order by either typing '1' or '2' in as the group number right before starting the inquisit task program, correct? Or does the program generate the group number and assign each participant to a group randomly? Thank you for your help! In Inquisit Lab, you'd type either 1 (for the first order: human -> dog) or 2 (for the second order: dog -> human) into the "Enter the group number:" field. When using Inquisit Web, you would instead select an suitable group number generation method in the web experiment's settings.
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