Status quo levels in discrete choice experiment

[JvB]

Dear Michiel,

so far I´ve used dummy coding for my estimations of the above mentioned model.
Is there any indication to use effects coding instead of dummy coding?
I´ve seen that some papers are using effects coding for categorical variables but am not sure if that might also make sense for my model.
I suppose no, because effects coding prevents from choosing the reference level arbitrarily, but as I have a fixed status quo dummy coding with SQ levels as reference levels seems to make most sense?!

Thankful for any information from your point of view!
Thanks and best,
J.

[JvB]

Sorry, this is the respective code:

Design
;alts = alt1*, alt2*, SQ*
;rows = 18
;block = 2
;eff = (mnl,d)
;alg = mfederov
;require:
SQ.amount = 3, SQ.period = 3
;reject:
alt1.amount = 3 AND alt1.period = 3,
alt2.amount = 3 AND alt2.period = 3
;model:
U(alt1) = b1[-0.0001] * contrib[1.8,2.5,3.2](6,6,6)
+ b2.dummy[0.0003|0.0002|0.0001] * amount[0,1,2,3] ? 0 = 300, 1 = 600, 2 = 900, 3 = unlimited amount
+ b3.dummy[0.0003|0.0002|0.0001] * period[0,1,2,3] ? 0 = 12, 1 = 42, 2 = 72, 3 = unlimited period
/
U(alt2) = b1 * contrib
+ b2 * amount
+ b3 * period
/
U(SQ) = b0[0]
+ b1 * contrib_sq[1.6]
+ b2 * amount
+ b3 * period
$

[Michiel Bliemer]

There is no real difference between dummy and effects coding as shown by Daly & Dekker & Hess (2016), so using dummy coding is perfectly fine and will make it easier to interpret parameters.

Daly, Dekker and Hess (2016) Dummy coding vs effects coding for categorical variables: Clarifications and extensions. Journal of Choice Modelling. https://www.sciencedirect.com/science/article/abs/pii/S1755534516300781

Michiel

[JvB]

Thank you very much for re-confirming, Michiel!