Meaning of mu parameter in nested logit

[Mwendwa Kiko]

Hi everyone,

I’m pretty new to biogeme, and I have a very basic question.

When specifying our nests for a nested logit model that we will then estimate using the biogeme.models.lognested() method, do the mu’s correspond to the scale parameter of the lower nest (in which case we want them to be >1) or to the scale parameter of the upper nest/scale parameter of the lower nest (in which case we want them to be <1)?

I’ve attached a photo of the code I’m currently working on:

I'm using Biogeme 3.2.8, and I haven't changed any of the default parameters.

[Bierlaire Michel]

By default, it is normalized from the top. Therefore, the nest parameter must be larger than 1.

> On 7 Apr 2023, at 00:38, Mwendwa Kiko <mwend...@gmail.com> wrote:
>
> Hi everyone,
> I’m pretty new to biogeme, and I have a very basic question.
> When specifying our nests for a nested logit model that we will then estimate using the biogeme.models.lognested() method, do the mu’s correspond to the scale parameter of the lower nest (in which case we want them to be >1) or to the scale parameter of the upper nest/scale parameter of the lower nest (in which case we want them to be <1)?

> I’ve attached a photo of the code I’m currently working on:<Code currently working on2.png>

>
> I'm using Biogeme 3.2.8, and I haven't changed any of the default parameters.
>

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> <Code currently working on2.png>

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