[R-sig-DCM] What is a strong covariate in CBC/HB?

[Wirth, Ralph (GfK SE)]

I'd say if the groups that are defined by the covariate are very different with regard to their preferences (i.e. utility parameters) and at the same time the members of each group are very homogeneous, then the covariate is a "strong" covariate.







-----Ursprüngliche Nachricht-----
Von: r-sig-dcm-bounces at r-project.org [mailto:r-sig-dcm-bounces at r-project.org] Im Auftrag von Dimitri Liakhovitski
Gesendet: Mittwoch, 2. März 2011 19:04
An: R DCM List
Betreff: [R-sig-DCM] What is a strong covariate in CBC/HB?

Guys, I could ask some of you individually but it's always better to talk to
several smart guys at a time.
Some of you know I am working on a project for an ART-Forum which explores
the issue of covariates in CBC/HB estimation: Is estimation with covariates
useful?

I have a question: what do YOU THINK is a "strong" covariate? (and let's
assume we know what the true utilities and their dependence on the covariate
are)
I am looking less for a mathematical answer (although it's OK if it is) and
more for a conceptual answer, maybe even with examples. Like: assume we have
a covariate with only 2 levels (i.e., respondents belong to 2 groups): what
should their preferences be like in order for us to be able to say: group
membership a strong covariate / weak covariate? And if we have 3 groups?
Also, I am looking less for a "correct" answer and more for your opinions.

Looking forward to your replies!

Dimitri Liakhovitski
ninah.com

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