Pilot study design for bayesian efficient design

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Re: Pilot study design for bayesian efficient design

Postby Steven Guu » Fri Jul 29, 2022 4:00 pm

Dear Michiel

I also have another question about the none option in the survey. Could I write your own current situation in the none option or I only can put I prefer none of these in the none option?

Thanks again.

Best
Steve
Steven Guu
 
Posts: 9
Joined: Wed Jun 15, 2022 12:54 am

Re: Pilot study design for bayesian efficient design

Postby Michiel Bliemer » Sat Jul 30, 2022 5:13 pm

Ngene reports a UTILITY balance of 99%, which has nothing to do with ATTRIBUTE LEVEL balance. The design is essentially 100% utility balanced because you are using zero priors such that the choice probabilities become 33-33-33% across the three alternatives.

You do not need utility balance in the design, nor do you need attribute level balance in the design, to be able to estimate your model. If your D-errors are not infinite, then you can estimate the model. It should be fine for the pilot study.

Michiel
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Re: Pilot study design for bayesian efficient design

Postby Steven Guu » Sun Jul 31, 2022 1:04 am

Dear Michiel

Thank you very much for advice. Sorry for keep asking these simple questions
Following your suggestions, to achieve attributes balance, I consider to use 12 rows, and block 3, in this case, people can keep facing 4 choice cards?
Do you think 16 rows is sufficient for the design?
In addition, if I also change blocks from 3 to 4, people will be shown 3 choice cards, which design do you think is better?
This is my codes
Design
;alts = alt1*,alt2*,none
;rows = 12
;block = 3,minsum
;eff = (mnl,d)
;con
;alg = mfederov(candidates=1000)

;model:
U(alt1) =b0[0]+ b1.dummy[0.001|0.002|0.003] * sorting[2,4,7,1]
+ b2.dummy[0.001|0.002] * collected[2,3,1]
+ b3.dummy[0.001|0.003] * point[2,3,1]
+ b4[-.001] * cost[20,40,60,80,100,200](1-2,1-2,1-2,1-2,1-2,1-2)
/
U(alt2) =b0+ b1*sorting+b2*collected+b3*point+b4*cost

$

Thank you very much for your time and help.

Best wishes
Steve
Steven Guu
 
Posts: 9
Joined: Wed Jun 15, 2022 12:54 am

Re: Pilot study design for bayesian efficient design

Postby Michiel Bliemer » Sun Jul 31, 2022 8:13 am

If you ask me, I would use the syntax below. It uses the default swapping algorithm so it has full attribute level balance. It uses 24 rows so it has sufficient variation, and it is blocked in 4 because people can easily answer 6 choice tasks. But you could block in more parts if you like, but if you only show 3 choice tasks to a respondent you obviously will need double the sample size to capture the same amount of information.

Code: Select all
Design
;alts = alt1*,alt2*,none
;rows = 24
;block = 4,minsum
;eff = (mnl,d)
;con
;model:
U(alt1) =b0[0]+ b1.dummy[0.001|0.002|0.003] * sorting[2,4,7,1]
+ b2.dummy[0.001|0.002] * collected[2,3,1]
+ b3.dummy[0.001|0.003] * point[2,3,1]
+ b4[-.001] * cost[20,40,60,80,100,200]
/
U(alt2) =b0+ b1*sorting+b2*collected+b3*point+b4*cost

$


Michiel
Michiel Bliemer
 
Posts: 1387
Joined: Tue Mar 31, 2009 4:13 pm

Re: Pilot study design for bayesian efficient design

Postby Steven Guu » Sun Jul 31, 2022 8:40 am

Dear Michiel

Thank you very much for your prompt and thorough explanation. Clear now. I really appreciate your time and help.

Best regards
Steven
Steven Guu
 
Posts: 9
Joined: Wed Jun 15, 2022 12:54 am

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