[R] MNP - discrete choice experiment

From: Felix Eggers <eggers_at_econ.uni-hamburg.de>
Date: Fri 16 Dec 2005 - 01:21:43 EST


Hello,

I need a little initial help with the MNP package.

I am trying to analyze a discrete choice experiment with the following settings:
- choice sets consist of 3 alternatives

The data frame ('example') would look like this (brand attribute is effect coded):

resp	y1	y2	y3	za1M	za1B	za2	zb1M	zb1B	zb2
zc1M	zc1B	zc2
A	1	0	0	1	0	50	0	1	50

-1 -1 50
A 1 0 0 1 0 50 0 1 100
-1 -1 100
A 1 0 0 1 0 50 0 1 150
-1 -1 150
A 0 1 0 1 0 200 0 1 50
-1 -1 200
B 0 0 1 1 0 100 0 1 100
-1 -1 50

...

Notation:
- resp respondent id

I tried the following mnp command for testing:

analysis <- mnp(cbind(y1, y2, y3) ~ 1,
 choiceX = list(y1=cbind(za1M, za1B, za2), y2=cbind(zb1M, zb1B, zb2),  y3=cbind(zc1M, zc1B, zc2)),
 cXnames = list("M", "B", "price"),
 data=example, n.draws=500, burnin=100, thin=3, verbose=TRUE)

My questions are:
1) How can I take into account that every respondent answers 4 choicesets? Or more generally, how can I obtain individual level estimates?

2) The MNP package description says that the choice specific variables are recorded relative to the baseline choice. But what if every choice set is different like in this case?

Any help will be appreciated!

Best regards,
Felix



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