Price elasticity and parameter restrictions

[Werg]

Hello everyone !

It's my very first time in this forum.
I'm trying use 2 prices as an exogenous in a ARIMAX model. But I need to define a restriction in the first price (because doesn't make sense increase the price and the sales increase to), and leave the second price (parameter) free.
I know it's possible apply a restriction (positive or negative) on input, but i don't know if it's possible define different rules for different inputs.

[udo_sas]

Hello -
Not sure if this makes sense, but it might be worthwhile to check out the MODEL procedure of SAS/ETS - see: http://support.sas.com/documentation/cdl/en/etsug/60372/HTML/default/etsug_model_sect048.htm
Thanks,
Udo

[Werg]

Hello Udo,

it's something like that, but I thought I could use the proc hpfdiagnose. In the Input Statement is possible define REQUIRED=MAYBE(NEGATIVE), but I don't need restrict all the variable inputs, but only the price.

Thanks !

[udo_sas]

Hi -
Have you considered using multiple INPUT statements?
HPFDIAG allows for that - so you would be able to specify different REQUIRED= statements for each of the variables if needed.
Thanks,
Udo

[Werg]

Udo, thanks a lot !

I'll try it.