Just wanted to query how to include “scenario” variables as in Section 8.5 of the manual ‘design within designs’. I didn’t find similar questions on the forum but please direct me if this has been suitably discussed before.
In our design we have three non-monetary attributes (att1, att2, att3) and one monetary (tax). On each choice card we provide pictures of a different species that the conservation plan could cover. This picture is the same across opt1, opt2, opt3 BUT varies across choice tasks. So, the first task pictures species1, the second species2 etc.
There are two research questions:
(1) how does the WTP for attributes 1,2,3 vary between medium and high levels,
(2) how does the species pictured on the choice card affect this WTP.
Minimum viable code:
- Code: Select all
Design
;alts=opt1*, opt2*, opt3
;rows=18
;block=2
;eff=(mnl,d)
;model:
U(opt1)=
b1.dummy[0.28|0.5] * att1[0,1,2] +
b2.dummy[0.14|0.25] * att2[0,1,2] +
b3.dummy[0.15|0.25] * att3[0,1,2] +
b4.dummy[-1|1] * species[0,1,2] +
b5[-0.25] * tax[ 1, 2, 3, 4, 5, 6]/
U(opt2)=
b1 * att1 +
b2 * att2 +
b3 * att3 +
b4 * species[species] +
b5 * tax /
U(opt3)= sq[-1.50]
$
Questions:
1) Should we specify interactions between the attributes and the species in this syntax?
2) Is this the correct approach to interpreting the effect of ‘scenario’ variables?
Thanks for all your insight here and in the manual, best
Peter