Number of blocks in main survey

This forum is for posts covering broader stated choice experimental design issues.

Moderators: Andrew Collins, Michiel Bliemer, johnr

Number of blocks in main survey

Postby firat85 » Mon Oct 19, 2020 7:27 pm

Dear all,

I'm about to start my main survey with a sample size of 600-700 participants that I hope to reach. My question is, would it provide enough variation for this sample size if I create 24 choice sets in total as three blocks consist of 8 choice sets? is there any criteria for this issue? Some papers in literature apply more for ex. 80 choice sets in 10 blocks.
firat85
 
Posts: 7
Joined: Thu Sep 24, 2020 5:19 am

Re: Number of blocks in main survey

Postby Michiel Bliemer » Wed Oct 21, 2020 8:27 am

That depends on the number of coefficients you are using as well as the number of alternatives in your choice model.

The number of choice tasks S needs to satisfy:

S*(J-1) >= K

where J is the number of alternatives and K is the number of coefficients you are estimating (including for dummy coded variables, interaction effects, etc).

The smallest S that satisfies the above is the MINIMUM number of choice tasks you need in your design (before blocking). But generally you will want to use a larger design than that to have enough variation, so you could choose to use something like 2*S, 3*S or 4*S to make sure that you have enough variation.

You may want to refer to Sandor and Wedel (2005), https://journals.sagepub.com/doi/abs/10.1509/jmkr.42.2.210.62285.

Michiel
Michiel Bliemer
 
Posts: 1705
Joined: Tue Mar 31, 2009 4:13 pm

Re: Number of blocks in main survey

Postby firat85 » Sun Oct 25, 2020 11:44 pm

Thank you for your answer Mr. Bliemer.
firat85
 
Posts: 7
Joined: Thu Sep 24, 2020 5:19 am


Return to Choice experiments - general

Who is online

Users browsing this forum: No registered users and 3 guests