Question on Threshold Parameter Specification in Hybrid Choice Model in Biogeme

[Ali Karami]

Dear Prof. Bierlaire,

In an ordinal measurement model for a hybrid choice framework, must one define a distinct set of threshold parameters (i.e. deltas and corresponding taus) for each individual indicator? Or is it statistically valid—and identifiable—to constrain a single set of thresholds and apply them uniformly across all indicators measuring the same latent variable?

Warm regards,
Ali

[Michel Bierlaire]

Usually, the set of thresholds is the same across indicators, as the measurement equations are meant to adjust the zero and the scale.

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Michel Bierlaire
Transport and Mobility Laboratory
School of Architecture, Civil and Environmental Engineering
EPFL - Ecole Polytechnique Fédérale de Lausanne
http://transp-or.epfl.ch
http://people.epfl.ch/michel.bierlaire